<PAGE>

               UNITED STATES SECURITIES AND EXCHANGE COMMISSION
                            WASHINGTON, D.C. 20549
                             _____________________
                                  FORM 10-K/A

                                Amendment No. 1

                                 ANNUAL REPORT
                    PURSUANT TO SECTION 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

                  For the fiscal year ended December 31, 1999

                        Commission File Number 0-20749

                           Aspect Development, Inc.
            (Exact name of registrant as specified in its charter)

           Delaware                                               25-1622857
(State or other jurisdiction of                               (I.R.S. Employer
incorporation or organization)                               Identification No.)

                 1395 Charleston Road, Mountain View CA 94043
             (Address of principal executive offices and zip code)

                                (650) 428-2700
             (Registrant's telephone number, including area code)
                        _______________________________

       Securities registered pursuant to Section 12(b) of the Act:  None

          Securities registered pursuant to Section 12(g) of the Act:

                   Common Stock, $0.001 par value per share
                               (Title of Class)

Indicate by check mark whether the Registrant (1) has filed all reports required
to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during
the preceding 12 months (or for such shorter period that the registrant was
required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.    Yes  X     No __
                                                 ---

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405
of Regulation S-K is not contained herein, will not be contained, to the best of
Registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K. [X]

The aggregate market value of the voting stock held by non-affiliates of the
Registrant, based upon the closing sale price of the Common Stock as reported on
the Nasdaq National Market on April 6, 2000, was approximately $3.3 billion. The
number of outstanding shares of the Registrant's Common Stock as of the close of
business on April 6, 2000 was 61,270,808.
<PAGE>

                                   PART III

All share and per share numbers in this Form 10-K/A have been adjusted to give
effect to a two-for-one stock dividend paid in March 2000.


ITEM 10.  DIRECTORS AND EXECUTIVE OFFICERS OF THE REGISTRANT

     The names of the current directors and executive officers, their ages and
certain information about them are set forth below:

<TABLE>
<CAPTION>
            Name                             Age                   Position Held With the Company
     <S>                                     <C>            <C>
     Dr. Romesh Wadhwani                     52             Chairman of the Board of Directors and Chief
                                                            Executive Officer
     Robert L. Evans                         47             President, Chief Operating Officer and
                                                            Director
     James C. Althoff                        46             Executive Vice President and Chief Technical
                                                            Officer
     David S. Dury                           51             Senior Vice President, Chief Financial Officer

     David J. Horne                          47             Senior Vice President

     Douglas M. Castek                       40             Vice President, Process and Services Business

     Donald K. Tomkinson                     42             Vice President, High Tech and Industrial
                                                            Sales
     Peter Ryan                              38             Vice President, and President of European
                                                            Operations
     Dennis G. Sisco                         53             Director

     Steven Goldby                           59             Director
</TABLE>

Dr. Wadhwani founded Aspect in 1990 and has served as Chairman of the Board of
Directors and Chief Executive Officer since January 1991.  From January 1982 to
March 1989, Dr. Wadhwani served as Chief Executive Officer of Cimflex
Teknowledge, Corp., a provider of factory automation products and systems.  Dr.
Wadhwani continued to serve as Chairman of the Board of Cimflex until July 1990.
From 1973 to 1981, Dr. Wadhwani was Chief Executive Officer of Compuguard
Corporation, a provider of building automation systems.  Dr. Wadhwani received
his M.S. and Ph.D. in Electrical Engineering from Carnegie-Mellon University.

Mr. Evans was elected President and Chief Operating Officer and Director of
Aspect in April 1999. From September 1995 to April 1999, Mr. Evans was a partner
at Andersen Consulting responsible for its Supply Chain Practices, Americas.
From November 1993 to September 1995, Mr. Evans was an associate partner at
Andersen Consulting responsible for its Logistics Strategy Practice.  From
September 1990 to August 1993, Mr. Evans was Vice President, Customer Support
for Mazda Motor of America, Inc.  Mr. Evans holds a B.A. in Economics from
MacMurray College and an M.A. in Economics from Western Illinois University.

Mr. Althoff joined Aspect as Vice President, Software Operations in December
1991 and was appointed Senior Vice President and Chief Technical Officer in
January 1997.  From October 1981 to December 1991, Mr. Althoff served in various
positions, including Vice President of Engineering and General Manager of the
Japan Business Unit of VLSI Technology/Compass Design & Automation, as ASIC
developer.  Mr. Althoff holds a B.S. in mathematics from Florida State
University and an M.S. in computer science from California Institute of
Technology.

                                       2
<PAGE>

Mr. Dury joined Aspect in April 1996 as Vice President and Chief Financial
Officer and was appointed Senior Vice President, Chief Financial Officer in
1999.  Mr. Dury served as Chief Financial Officer of NetFrame Systems, Inc., a
network server manufacturer, from March 1992 to April 1996. From August 1991 to
February 1992, Mr. Dury served as Senior Vice President and Chief Financial
Officer of Maxtor Corporation, a disk drive manufacturer. From December 1989 to
August 1991, Mr. Dury served as Executive Vice President and Chief Financial
Officer of Boole & Babbage, a software developer. Mr. Dury was employed by Priam
Corporation from February 1983 to February 1989, serving first as Vice President
and Chief Financial Officer, and then as President and Chief Operating Officer.
Mr. Dury had several financial and operating management positions at Intel
Corporation from 1979 to 1983. Mr. Dury holds a B.A. in psychology from Duke
University and an M.B.A. from Cornell University.

Mr. Horne joined Aspect in September 1996 as Vice President of Marketing and was
appointed Senior Vice President in 1999. Mr. Horne was Vice President of
Marketing for Concentra Corporation, a sales process automation software
company, from July 1994 to September 1996.  From September 1982 to June 1994, he
held a variety of sales and marketing management positions at Computervision
Corporation, a software development company, most recently Director of Worldwide
Marketing operations. Mr. Horne holds a B.S. from the University of
Massachusetts and an M.B.A. from Northeastern University.

Mr. Castek joined Aspect as Vice President, Process and Services Business in
October 1999.  From September 1997 to September 1999, Mr. Castek was a partner
with Andersen Consulting in their Strategic Services Supply Chain Practice.
From September 1995 to August 1997, Mr. Castek was an associate partner with
Andersen Consulting in their Strategic Services Supply Chain Practice.  From
December 1993 to September 1995, Mr. Castek was Senior Manager with Andersen
Consulting in their Strategic Services Supply Chain Practice.  Prior to his six
years at Andersen Consulting, Mr. Castek spent an additional eight years in
consulting with Coopers & Lybrand (now PriceWaterhouseCoopers).  Mr. Castek has
also held positions with Avco Lycoming (now owned by Allied Signal) and Goodyear
Tire and Rubber Company.  Mr. Castek holds a degree in Industrial Management
from Purdue University.

Mr. Tomkinson joined Aspect as Practice Director in October 1996 and was
appointed Vice President, High Tech and Industrial Sales in January 1999.  From
November 1995 to October 1996, Mr. Tomkinson was Vice President of Operations
for Scicom, a telecom/datacom software development company.  From May 1994 to
November 1995, Mr. Tomkinson was Director of Worldwide Services at
Telecommunications Techniques Corporation.  From January 1988 to May 1994, Mr.
Tomkinson held a variety of marketing management positions at Computervision
Corporation, a software development company, most recently Director of
Integrated Support Services.  Mr. Tomkinson holds an Industrial Engineering
degree from the University of Rhode Island and an MBA from the University of
Maine.

Mr. Ryan joined Aspect as President of European Operations in October 1999.
Before joining Aspect, Mr. Ryan was Divisional Vice President - Europe for
Parametric Technology Corporation from June 1999 to September 1999.  From 1988
to 1998 he held a variety of management positions at IBM Corporation, most
recently Director of Engineering Technology Solutions, Europe, Middle East and
Africa.

Mr. Goldby was elected to Aspect's Board of Directors in March 1993.  Mr. Goldby
has been Chairman and Chief Executive Officer of Symyx Technologies Inc., a
chemical, electronic and life science materials research and development
company, since July 1998.  Until December 1999, Mr. Goldby was Chairman of the
Board of Directors and, earlier, Chief Executive Officer of MDL Information
Systems, Inc., an enterprise software company, where he was employed since
January 1982.  Mr. Goldby is also a director of Peoplesoft, Inc.

Mr. Sisco was elected to Aspect's Board of Directors in September 1994.  Mr.
Sisco has been a partner in Behrman Capital, a private equity investment firm,
since January 1998.  Mr. Sisco was an Executive Vice President at Cognizant
Corporation, an information services company, from February 1995 until February
1997.  Prior to that time, beginning in July 1993, Mr. Sisco was a Senior Vice
President at Dun & Bradstreet Corporation.  Mr. Sisco was also President of
Cognizant Enterprises, a venture capital firm, from December 1988 until February
1997.  Mr. Sisco also serves as a director of TSI Software International, Inc.,
a software products firm, The Management Network Group, Inc., a consulting firm
providing services to the telecommunications industry, and Gartner Group, Inc.,
a technology advisory and research firm.

                                       3
<PAGE>

COMPLIANCE WITH SECTION 16 (A) OF THE EXCHANGE ACT

     Section 16(a) of the Securities Exchange Act of 1934 (the "Exchange Act")
requires the Company's directors and executive officers, and persons who own
more than ten percent of a registered class of the Company's equity securities,
to file with the Securities and Exchange Commission (SEC) initial reports of
ownership and reports of changes in ownership of common stock and other equity
securities of the Company.  Officers, directors and greater than ten percent
stockholders are required by SEC regulation to furnish the Company with copies
of all Section 16(a) forms they file.

     To Aspect's knowledge, based solely on a review of the copies of such
reports furnished to Aspect and written representations that no other reports
were required, during the fiscal year ended December 31, 1999, all Section 16(a)
filing requirements applicable to its officers, directors and greater than ten
percent beneficial owners were complied with.

ITEM 11.  EXECUTIVE COMPENSATION

                           COMPENSATION OF DIRECTORS

Employee directors of Aspect receive no compensation for their services as
directors.  Non-employee directors of Aspect receive five thousand dollars for
their services as directors.  All directors are eligible for reimbursement for
their expenses incurred in connection with attendance at Board meetings in
accordance with company policy.

Prior to 1999, each non-employee director also received nonstatutory stock
options under the 1996 Outside Directors Stock Option Plan (Directors Plan).  In
1999, the Company terminated future grants under the Directors Plan.  During
fiscal year 1999, each non-employee director was eligible to receive
nonstatutory stock options under the Amended and Restated 1992 Stock Option Plan
(1992 Plan) and the 1997 Nonstatutory Stock Option Plan (1997 Plan).

Option grants under the 1992 Plan and the 1997 Plan are non-discretionary.  On
May 23, 1996, each individual then serving as a non-employee director received
an initial option grant of 20,000 shares of common stock from the Directors
Plan, except for Steven Goldby who received an initial option grant of 120,000
shares of common stock from the 1992 Plan on May 5, 1992.  Each individual
subsequently elected for the first time to serve as a non-employee director
receives an option grant covering 60,000 shares (Initial Option) from the
Directors Plan, and beginning in fiscal year 1999, from the 1992 Plan.  On the
first business day following each of Aspect's annual meetings of stockholders,
each non-employee director is automatically granted an option to purchase an
additional 20,000 shares of Aspect common stock (Annual Option).  The exercise
price of options granted under both the 1992 Plan and 1997 Plan is 100% of the
fair market value of Aspect's common stock on the date of the option grant.
Initial Options vest at a rate of 25% one year after grant date and 1/48 each
month thereafter of optionee's continuous service until fully vested.  Annual
Options vest at a rate of 8.33% one month immediately after grant date and 1/12
thereafter of optionee's continuous service until fully vested.

During the last fiscal year, options covering 20,000 shares were granted to each
non-employee director from the 1992 Plan at an exercise price per share of
$13.06, and options covering 20,000 shares were granted to each non-employee
director from the 1997 Plan at an exercise price per share of $8.56.  As of
April 4, 2000, 9,996 options had been exercised under the 1997 Plan.


                      COMPENSATION OF EXECUTIVE OFFICERS

                          Summary Compensation Table

     The following table shows for the fiscal years ended December 31, 1999,
1998 and 1997, compensation awarded or paid to, or earned by, (i) all
individuals who have served as the Company's Chief Executive Officer during 1999
and (ii) the Company's four other most highly compensated executive officers at
December 31, 1999 (collectively, the "Named Executive Officers"):

                                       4
<PAGE>

<TABLE>
<CAPTION>
                                                                                     Long-Term
                                                                                    Compensation
                                                        Annual Compensation            Awards
                                                        -------------------            ------
                                                                                     Securities
                                                                                     ----------
                                                                                     Underlying
                                                                                     ----------
Name and Principal                                     Salary          Bonus          Options        All Other
                                                       ------          -----          -------        ---------
     Position                           Year             ($)            ($)             (#)      Compensation ($)
     --------                           ----             ---            ---             ---      ----------------
<S>                                     <C>            <C>            <C>            <C>            <C>
Romesh Wadhwani                         1999           216,667        116,563        2,440,000      21,789 (1)
Chief Executive Officer                 1998           200,000        100,000        1,500,000              -
                                        1997           200,000        100,000          500,000       4,337 (2)

Robert L. Evans (3)                     1999           214,808         75,000        1,200,000              -
President, Chief Operating              1998                --              -                -              -
Officer                                 1997                --              -                -              -

Donald K. Tomkinson                     1999           147,917        134,377          280,000              -
Vice President, High Tech               1998           105,030         67,500           64,000              -
and Industrial Sales                    1997           119,259         70,044           20,000              -

David S. Dury                           1999           188,750         63,410          210,000              -
Senior Vice President and               1998           170,000         51,350           60,000              -
Chief Financial Officer                 1997           169,209         37,500           40,000              -

James C. Althoff                        1999           185,039         48,975          200,000              -
Executive Vice President and            1998           182,771         73,298          140,000              -
Chief Technical Officer                 1997           159,597         48,373          140,252              -
</TABLE>

     (1)  Represents amounts paid by the Company for executive life insurance
          and long-term disability insurance. $11,420 was paid for executive
          life insurance for which Dr. Wadhwani's estate is the beneficiary,
          $5,230 was paid for executive life insurance for which Mr. Evans is
          the beneficiary, and $5,139 was paid for long-term disability
          insurance.

     (2)  Represents amounts paid by the Company for executive life insurance
          for which Dr. Wadhwani's estate is the beneficiary.

     (3)  Mr. Evans joined the Company in April 1999.

                                       5
<PAGE>

                       STOCK OPTION GRANTS AND EXERCISES

     The Company grants options to its executive officers under its Amended and
Restated 1992 Stock Option Plan (1992 Plan), and the 1997 Nonstatutory Stock
Option Plan (1997 Plan).  The following tables show, for the fiscal year ended
December 31, 1999, certain information regarding options granted to, exercised
by, and held at year-end by, the Named Executive Officers:

                       Option Grants in Last Fiscal Year

<TABLE>
<CAPTION>
                         Individual Grants
                     Number of        % of Total                                    Potential Realizable
                     Securities        Options                                       Value at Assumed
                     Underlying       Granted to                                     Annual Rates of
                      Options         Employees   Exercise                             Stock Price
                      Granted         In Fiscal    Price      Expiration         Appreciation for Option
                       (#) (1)         Year(2)     ($/Sh)        Date                    Term(3)
                       -------         -------     ------        ----                    -------
Name                                                                             5% ($)           10% ($)
----                                                                             ------           -------
<S>                  <C>              <C>         <C>         <C>              <C>              <C>
Dr. Wadhwani          1,840,000        13.68%        3.47      4/14/09         4,022,424        10,151,832
                        600,000         4.46%       13.06     10/18/09         4,936,680        12,459,240

Mr. Evans               840,000         6.24%        3.47      4/14/09         1,836,324         4,634,532
                         60,000         0.45%        3.47       9/9/09           131,166           331,038
                        300,000         2.23%       13.06     10/18/09         2,468,340         6,229,620

Mr. Tomkinson           130,000         0.97%        3.47      4/14/09           284,193           717,249
                         20,000         0.15%        7.50      8/20/09            94,500           238,500
                         50,000         0.37%        9.25       9/9/09           291,375           735,375
                         80,000         0.59%       13.06     10/18/09           658,224         1,661,232

Mr. Dury                 90,000         0.67%        3.47      4/14/09           196,749           496,557
                        120,000         0.89%       13.06     10/18/09           987,336         2,491,848

Mr. Althoff             200,000         1.49%        3.47      4/14/09           437,220         1,103,460
</TABLE>

(1)  Options generally vest over four years. In the event of a sale, merger or
consolidation, sale of substantially all the assets or dissolution of Aspect
(each a "Change of Control"), the surviving corporation may either assume
outstanding options or substitute similar options for those outstanding under
the 1992 Plan and 1997 Plan.  Options that are not assumed, substituted or
exercised prior to a Change of Control shall terminate on the occurrence of the
Change of Control.

(2)  Based on options to purchase an aggregate of 13,450,958 shares granted to
employees (including employee directors) during the fiscal year ended December
31, 1999. The foregoing total excludes options granted to consultants and non-
employee directors.  There were no stock appreciation rights granted during
1999.

(3)  The potential realizable value is based on the term of the option at its
time of grant.  It is calculated by assuming that the stock price on the date of
grant appreciates at the indicated annual rate, compounded annually for the
entire term of the option and that the option is exercised and sold on the last
day of its term for the appreciated stock price. These amounts represent certain
assumed rates of appreciation only, in accordance with the rules of the SEC, and
do not reflect Aspect's estimate or projection of future stock price
performance. Actual gains, if any, are dependent on the actual further
performance of the common stock, and no gain to the optionee is possible unless
the stock price increases over the option term.

                                       6
<PAGE>

  Aggregated Option Exercises in Last Fiscal Year, and Fiscal Year-End Option
                                     Values


<TABLE>
<CAPTION>
                                                                           Number of Securities
                                                                                Underlying
                                                                            Unexercised Options         Value of Unexercised
                                                                               At FY-End (#)           In-the-Money Options at
                                    Shares Acquired   Value Realized           Exercisable/            FY-End ($) Exercisable/
                                    On Exercise (#)       ($)/(1)            Unexercisable/(2)             Unexercisable/(3)
                                    ---------------       -------            -----------------             ----------------
     Name
     ----
     <S>                            <C>               <C>                  <C>                         <C>
     Dr. Wadhwani                             -                 -           2,211,665/2,735,989         56,569,549/73,111,840

     Mr. Evans                                -                 -             139,999/1,060,001          4,309,169/29,403,031

     Mr. Tomkinson                       90,628         1,311,011                 3,354/308,418              84,553/7,950,238

     Mr. Dury                           124,000         2,912,440                98,465/302,335           3,048,347/7,767,853

     Mr. Althoff                        110,000         1,276,500               158,305/311,947           4,657,780/8,897,980
</TABLE>

_____________________
(1)  Market value of the underlying securities on the exercise date minus the
     exercise price of such options.

(2)  Unvested options to purchase shares granted under Aspect's stock option
     plans are immediately exercisable subject to a right of repurchase by
     Aspect which lapses over time.

(3)  Based on the $34.25 per share closing price of Aspect's common stock on the
     Nasdaq National Market on December 31, 1999, less the exercise prices.


     EMPLOYMENT CONTRACTS, TERMINATION OF EMPLOYMENT AND CHANGE-IN-CONTROL
                                 ARRANGEMENTS

Change-in-Control Arrangements

     In addition to the provisions in the 1992 Plan and 1997 Plan relating to
Changes of Control, the agreement with respect to certain options granted to Dr.
Wadhwani provides that, in the event of a transfer of control, any
unexerciseable or unvested options will be immediately exerciseable and vested
in full 10 days before the date of a transfer of control. The agreement with
respect to certain options granted to Mr. Evans provides that, in the event
Aspect is acquired by another entity, and Mr. Evans continues as an employee as
President and Chief Operating Officer, then half of any remaining unvested
options will vest immediately.  In the event of an acquisition after which Mr.
Evans is constructively discharged, then all remaining unvested options will
vest immediately.  The agreements with respect to certain options granted to Mr.
Tomkinson and Mr. Althoff provide that, in the event of a change in control,
half of the remaining unvested options will vest immediately.  The agreement
with respect to certain options granted to Mr. Dury provide that, in the event
of a change of control, half of the remaining unvested options will vest
immediately.  In addition, if Mr. Dury is constructively discharged, then all
remaining unvested options will vest immediately.

Termination Arrangements

     Mr. Evans's employment offer letter contains a provision requiring Aspect
to pay Mr. Evans half of his current base salary and half of the incentive bonus
paid in the previous year if Aspect involuntarily terminates his employment.
These amounts will be paid, if at all, monthly over six months, following the
date of any such termination.

                                       7
<PAGE>

ITEM 12. SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT

     The following table sets forth certain information regarding the ownership
of the Company's common stock as of April 1, 2000 by: (i) each director; (ii)
each of the Named Executive Officers; (iii) all current executive officers and
directors as a group; and (iv) all those known to be beneficial owners of more
than five percent of Aspect's common stock.

<TABLE>
<CAPTION>
                                                                                          Beneficial Ownership /(1)/
                                                                                       -------------------------------
                                                                                          Number           Percent of
                              Beneficial Owner                                          of Shares             Total
-------------------------------------------------------------------------------        -----------         -----------
<S>                                                                                    <C>                 <C>
Romesh Wadhwani /(2)/
  1395 Charleston Road
  Mountain View, CA 94043......................................................         14,810,000             22.38%
FMR Corp.  /(3)/
  82 Devonshire Street
  Boston, MA 02019.............................................................          5,122,106              8.37%
Robert L. Evans /(4)/..........................................................          1,026,000              1.65%
James Althoff /(5)/............................................................            619,528              1.01%
Steven Goldby /(6)/............................................................             70,004              *
David S. Dury /(7)/............................................................            422,108              *
Dennis G. Sisco /(8)/..........................................................            144,000              *
Donald Tomkinson /(9)/.........................................................            288,730              *
All directors and current executive officers as a group (10 persons) /(10)/....         18,413,388             26.50%
</TABLE>

_____
*Less than 1%.

(1)  Beneficial ownership is determined in accordance with the rules of the SEC,
     based on factors including voting and investment power. Shares of common
     stock subject to options currently exercisable or exercisable within 60
     days after April 1, 2000 are deemed outstanding for computing the
     percentage ownership of the person or entity holding such securities, but
     are not deemed outstanding for computing the percentage ownership of any
     other person or entity. To Aspect's knowledge, the persons named in this
     table have sole voting and investment power with respect to all shares of
     common stock shown as beneficially owned by them, subject to community
     property laws where applicable and except as indicated in the other
     footnotes to this table. Applicable percentage of beneficial ownership is
     based on 61,221,673 shares of common stock outstanding as of April 1, 2000,
     net of treasury stock.

(2)  Includes 4,940,000 shares subject to immediately exercisable options held
     by Dr. Wadhwani, 2,261,668 of which are subject to a right to repurchase by
     Aspect, which right lapses over time.

(3)  Consists of: 4,022,066 shares held by Fidelity Management & Research
     Company (Fidelity), which is a wholly-owned subsidiary of FMR Corp.;
     1,070,200 shares held by Fidelity Management Trust Company, which is a
     wholly-owned subsidiary of FMR Corp.; 29,840 shares held by Fidelity
     International Limited and various foreign-based subsidiaries which provide
     investment advisory and management services to a number of non-U.S.
     investment companies. Based upon information supplied in Schedule 13G filed
     with the SEC in February 2000.

(4)  Includes 1,026,000 shares subject to immediately exercisable options held
     by Mr. Evans, 962,501 of which are subject to a right to repurchase by
     Aspect, which right lapses over time.

(5)  Includes 410,252 shares subject to immediately exercisable options held by
     Mr. Althoff, 229,723 of which are subject to a right to repurchase by
     Aspect, which right lapses over time.

(6)  Includes 70,004 shares subject to immediately exercisable options held by
     Mr. Goldby, 63,335 of which are subject to a right to repurchase by Aspect,
     which right lapses over time.

(7)  Includes 360,800 shares subject to immediately exercisable options held by
     Mr. Dury, 223,000 of which are subject to a right to repurchase by Aspect,
     which right lapses over time.

(8)  Includes 140,000 shares subject to immediately exercisable options held by
     Mr. Sisco, 59,585 of which are subject to a right to repurchase by Aspect,
     which right lapses over time.

(9)  Includes 288,730 shares subject to immediately exercisable options held by
     Mr. Tomkinson, 265,661 of which are subject to a right to repurchase by
     Aspect, which right lapses over time.

(10) Includes shares described in the notes above, as applicable. Includes
     8,264,494 shares subject to stock options held by all executive officers
     and directors, as a group, exercisable within 60 days of April 1, 2000.

                                       8
<PAGE>

ITEM 14. EXHIBITS, FINANCIAL STATEMENT SCHEDULES, AND REPORTS ON FORM 8-K



     (a)  The following financial statements and supplemental data are included
          in Item 8 of the Registrant's 1999 Annual Report on Form 10-K:


          (1)  Financial Statements

Report of Arthur Andersen LLP, Independent Public Accountants

Report of Ernst & Young LLP, Independent Auditors

Report of Arthur Andersen LLP, Independent Public Accountants

Consolidated Balance Sheets as of December 31, 1999 and 1998

Consolidated Statements of Operations for each of the three fiscal years in
the period ended December 31, 1999

Consolidated Statements of Stockholders' Equity for each of the three fiscal
years in the period ended December 31, 1999

Consolidated Statements of Cash Flows for each of the three fiscal years in
the period ended December 31, 1999

Notes to the Consolidated Financial Statements

          (2)  Financial Statement Schedules

          Schedule II - Valuation and Qualifying Accounts

          All other schedules are omitted because they are not applicable, or
          not required, or because the required information was filed by the
          Company's previously, or is included the consolidated financial
          statements or notes thereto.

          (3)  Exhibits

          The following exhibits are filed as part of, or incorporated by
reference into, this Report.

<TABLE>
<CAPTION>
  Exhibit
  Number                       Description of Document
  ------                       -----------------------
<S>            <C>
  3.1(7)       Restated Certificate of Incorporation, as amended to date.
  3.2(1)       By-Laws.
  4.1(1)       Restated Rights Agreement dated December 3, 1993.
*10.1(1)       Amended and Restated 1992 Stock Option Plan and forms of
               agreement thereunder.
*10.2(1)       1996 Employee Stock Purchase Plan.
*10.3(1)       1996 Outside Directors Stock Option Plan and forms of agreement
               thereunder.
 10.4(7)       1997 Nonstatutory Stock Option Plan and forms of agreement
               thereunder.
 10.5(1)       Sublease Agreement between the Registrant and Insignia Solutions,
               Inc. dated December 9, 1995.
 10.6(1)       Agreement of Lease between the Registrant and Mareld Company,
               Inc. dated June 2, 1994.
 10.7(1)       Agreement of Lease between Aspect Development India and
               M.S. Janardhan Corporation dated September 18, 1995.
 10.8(1)       Agreement of Lease between Aspect-DCM Pvt. Ltd. and the co-
               owners of Leo Shopping Complex dated February 10, 1994.
 10.9(1)       Master Lease Agreement between the Registrant and Comdisco, Inc.
               dated July 2, 1992.
10.10(1)       Business Loan Agreement between the Registrant and Silicon Valley
               Bank dated November 14, 1995.
10.11(2)       Agreement and Plan of Reorganization dated November 18, 1997
               among Aspect Development, Inc., Hawaii
               Acquisition Corporation and Cadis, Inc.
10.12(2)       Amendment to Agreement and Plan of Reorganization dated November
               21, 1997 among Aspect Development, Inc., Hawaii Acquisition
               Corporation and Cadis, Inc.
10.13(3)       Rights Agreement dated as of October 7, 1998 between the
               Registrant and U.S. Stock Transfer Corporation.
10.14(5)       Agreement and Plan of Reorganization between Aspect Development,
               Inc., Asta Merger Sub, Inc. and Transition Analysis Component
               Technology, Inc. dated January 17, 2000.
10.15(5)       Amendment No. 1 to Agreement and Plan of Reorganization dated
               April 6, 2000.
10.16(6)       Agreement and Plan of Merger and Reorganization, dated as of
               March 12, 2000, by and among i2 Technologies, Inc., Hoya Merger
               Corp. and Aspect Development, Inc.
21.1 (4)       List of Subsidiaries.
</TABLE>

                                       9
<PAGE>

 23.1 (4)      Consent of Arthur Andersen LLP, Independent Public Accountants.
 23.2 (4)      Consent of Ernst & Young LLP, Independent Auditors.
 23.3 (4)      Consent of Arthur Andersen LLP, Independent Public Accountants.
 27.1 (4)      Financial Data Schedule.

********

*    Constitutes a management contract or compensatory plan required to be
     filed pursuant to Item 13(a) of Form 10-K.

(1)  Incorporated by reference to Registrant's Registration Statement on Form
     SB-2 (file no. 333-3840-LA) filed on April 19, 1996.
(2)  Incorporated by reference to Registrant's Current Report on Form 8-K
     filed December 10, 1997.
(3)  Incorporated by reference to Registrant's Current Report on Form 8-K
     filed October 7, 1998.
(4)  Incorporated by reference to Registrant's Annual Report on Form 10-K filed
     March 30, 2000.
(5)  Incorporated by reference to Registrant's Registration Statement on
     Form S-4 filed April 11, 2000.
(6)  Incorporated by reference to Registrant's Schedule 13D filed March 22,
     2000.
(7)  Incorporated by reference to Registrant's Annual Report on Form 10-K/A
     filed April 30, 1999.

(b)  Reports on Form 8-K during the quarter ended December 31, 1999:

  None.

                                       10
<PAGE>

                                  SIGNATURES

     Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the registrant has duly caused this Form 10-K/A to be
signed on its behalf by the undersigned, thereunto duly authorized.

                                         ASPECT DEVELOPMENT, INC.


Date: April 18, 2000                     By:   /s/ David S. Dury
                                         ---------------------------------------
                                         David S. Dury
                                         Senior Vice President and
                                         Chief Financial Officer

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