<PAGE>

                                  EXHIBIT 4.1

                         JACOBS ENGINEERING GROUP INC.

                       1989 EMPLOYEE STOCK PURCHASE PLAN

                           (As Amended and Restated)

     1.  Purposes of the Plan.

     This Employee Stock Purchase Plan (the "Plan") is intended to encourage
stock ownership by employees of Jacobs Engineering Group Inc. (the "Company")
and certain subsidiaries of the Company.  The Plan is intended to qualify as an
employee stock purchase plan under Section 423 of the Internal Revenue Code (the
"Code").

     2.  Administration.

     The Plan shall be administered by a committee (the "Committee") appointed
by the Board of Directors of the Company (the "Board") from among its members
and shall be comprised of not less than three (3) members of the Board.  Unless
and until its members are not qualified to serve on the Committee pursuant to
the provisions of the Plan, the Compensation Committee of the Board shall
function as the Committee.  Members of the Committee shall be members of the
Board who are not eligible to participate under the Plan or any other plan of
the Company or its affiliates authorizing discretionary grants or awards of
stock, stock options or stock appreciation rights and who have not been eligible
to so participate for at least one (1) year prior to service as an administrator
of the Plan.  Eligibility requirements for members of the Committee shall comply
with Rule 16b-3 promulgated pursuant to the Securities Exchange Act of 1934, as
amended (the "1934 Act") or any successor rule or regulation.  No person, other
than members of the Committee, shall have any discretion concerning decisions
regarding the Plan except as otherwise provided in this Plan.  The Committee is
authorized to construe and interpret the Plan, to define the terms used herein,
to prescribe, amend and rescind rules and regulations for the administration of
the Plan, and to take any other action in connection with the administration of
the Plan and Options granted hereunder that it deems proper.

     3.  Grant of Options.

     (a) The Company shall grant to all Eligible Employees Options ("Options")
to purchase Common Stock of the Company ("Shares") in accordance with this Plan.
All employees granted Options under the Plan shall have the same rights and
privileges.

     (b) The Options granted under this Plan shall be granted effective only on
the first day of a six month election period referred to in Paragraph 5 of the
Plan ("Election Period").  No Option shall be treated as granted prior to the
first day of such Election Period.

     4.  Eligible Employees.

     (a) The employees eligible to receive Options under the Plan ("Eligible
Employee") shall be all employees of the Company and all corporations that now
are or hereafter become domestic United States subsidiary corporations (as
defined in Section 424(f) of the Code) and all employees of any foreign
subsidiary corporation designated from time to time by the Board of Directors.
The Board of Directors of the Company may change the designation of the
subsidiaries participating in the Plan ("participating subsidiaries") at any
time.

     (b) However, the following employees shall not be Eligible Employees under
the Plan:

         (i)    Employees who normally work fewer than 20 hours per week;

         (ii)   Employees who normally work five or fewer months during the
                fiscal year of the Company;

         (iii)  Employees who have completed less than one year of employment
                by the Company or a participating subsidiary of the Company; and

                                       1
<PAGE>

         (iv)   Employees who are not actively employed by the Company at the
                beginning of a six month Election Period, including employees
                who are on disability leave or leave of absence.

     (c) Employees of participating subsidiaries that have become subsidiaries
by reason of having been acquired by the Company or a subsidiary and companies
that have been merged with the Company or a subsidiary shall, in the discretion
of the Committee, receive credit for the time they have worked for such acquired
or merged company.

     (d) Any employee who would own more than five percent of the Common Stock
in the Company immediately after an Option under this Plan is granted shall also
be excluded from eligibility.  Stock that the employee may purchase under all
outstanding stock options granted to him or her by the Company shall be treated
as stock owned by the employee for such purposes, even though the option is not
presently exercisable.

     5.  Exercise of Option

     (a) An Eligible Employee may exercise his or her Option to acquire Common
Stock by completing a Payroll Deduction Authorization Form in such form as shall
have been approved from time to time by the Committee.  The election to exercise
the Option shall be effective for a six month election period.  The six month
Election Periods shall be from September 1 to February 28/29, and from March 1
to August 31 of each year.  An Eligible Employee's election to participate in
this Plan shall be irrevocable during each Election Period.

     (b) Eligible Employees who have elected to exercise their Options for any
Election Period are sometimes referred to as "Participants" in this Plan.

     (c) In no event may an Option be exercised later than the period of time
specified in Section 423(b)(7)(B) of the Code.  Except as otherwise provided in
Paragraph 12, an Option shall be treated as exercised on the last day of the six
month Election Period.

     6.  Payment of Purchase Price.

     (a) Each Participant shall pay for the stock subject to his or her option
with after-tax salary reduction contributions.  The Company shall reduce each
Participant's salary or wages by any whole percentage from 2% to 15% of basic
compensation.  A Participant's basic compensation shall include only regular
fixed basic compensation, and shall not include any bonus, overtime payment,
contribution to an employee benefit plan or other similar payment or
contribution.

     (b) Each Participant shall specify the amount of salary reduction on a
Payroll Deduction Authorization Form to be furnished by the Company.  The salary
reduction contributions shall continue throughout the six month Election Period.

     (c) The Company shall begin salary reductions during the pay periods as
close as practicable to each March 1 and September 1 of each year and shall
cease such reductions during the pay periods as close as practicable to each
February 28/29 and August 31 of each year.

     (d) As soon as practicable after the end of each six month Election Period,
the Company shall issue to the Participants who have exercised their Options
Common Stock of the Company at the prices specified in Paragraph 8 of this Plan.
The number of Shares purchased shall be based upon the aggregate amount of
salary reduction contributions during the six month Election Period plus any
excess contributions carried forward from any previous Election Period.  No
interest shall accrue on the salary reduction contributions.

     7.  Fractional Shares.

     The Company shall not issue or transfer fractional Shares under the Plan.
In the event that the amount of salary reduction contributions of any employee
is not exactly equal to the purchase price for a whole number of Shares, then
any excess amount shall be used to purchase additional Shares during the next
six month Election Period, or refunded to the Participant without interest if
the Participant is not, for any reason, a Participant in the Plan during the
next six month Election Period.

                                       2
<PAGE>

     8.  Purchase Price.

     (a) The purchase price for the Shares shall be the lower of (a) 90% of the
fair market value of the Shares on the first day of a six month Election Period
for which an Option has been exercised, or (b) 90% of the fair market value of
the Shares on the last day of such Election Period; provided, however, that the
Committee may at such time as it deems such change desirable and in the best
interests of the Company, approve, in lieu of the foregoing formula for
determining the exercise price of Options under this Plan, the fair market value
of the Shares on the last day of the Election Period multiplied by any
percentage figure from 85% to 100% as selected by the Committee.  Such approval
may be for one or more Election Periods and shall remain in effect until changed
by the Committee.

     In no event, however, may the Committee select a purchase price that would
be lower than that allowed under Section 423(b)(6) of the Code or any successor
section.

     (b) The fair market value for such purposes shall be the closing price of
the Shares on the composite transactions report of the national securities
exchange on which the Shares are then listed for the day on which the value is
to be determined.  If such date is a Saturday, Sunday, legal holiday or other
date on which such exchange is closed, then the fair market value shall be
determined as the closing price on the first immediately preceding trading date.

     9.  Stock Subject to the Plan.

     The total number of Shares of Common Stock authorized to be issued under
this Plan is 5,406,777 Shares, subject to adjustment as provided in Paragraph
17.  These Shares may be authorized but unissued Shares, or issued Shares which
have been reacquired by the Company from any person.

     10. Maximum Amount of Option Stock.

     (a) The maximum fair market value of Shares that an employee may accrue the
right to purchase under the Plan and any other employee stock purchase plan of
the Company or any subsidiary in any calendar year may not exceed $25,000 or
such greater amount as Section 423(b)(8)(C) of the Code, or any successor
section, may hereafter allow.  The fair market value of the Shares for such
purposes shall be determined on the first day of each six month Election Period.

     (b) The maximum number of Shares that a Participant may purchase for any
six month Election Period shall be determined on the first day of each Election
Period and shall be based upon the assumption that the Participant's basic
compensation will not change after such first day of the Election Period.  The
maximum number of shares shall be equal to the product obtained by multiplying
(a) the quotient obtained by dividing 15% of the total basic compensation to be
earned by the Participant during the six month Election Period by an amount
equal to 90% of the fair market value of the Common Stock on the first day of
the Election Period by (b) one and one-half (1 1/2).  Subject to the limitation
contained in the first paragraph of this Paragraph 10, any excess withholdings
resulting from this limitation shall be used to buy Common Stock during the next
six month Election Period or refunded to the employee without interest in the
event that the employee does not elect to purchase Common Stock during the next
six month Election Period.

     11. Restrictions on Transferability.

     A Participant may not transfer an Option other than by will or the laws of
descent and distribution.  Only the Participant may exercise an Option during
his or her lifetime.

     12. Termination of Employment.

     In the event that a Participant ceases to be employed by the Company or a
participating subsidiary for any reason, including death, disability, retirement
or voluntary or involuntary termination, then the Participant's rights under the
Plan shall terminate.  Except as provided in Paragraph 13, below, the Company
shall refund to the Participant without interest the salary reduction
contributions made by the Participant during the Election Period in which
termination occurs.

     13. Designation of Beneficiary.

     (a) A Participant may file, in a manner prescribed by the Committee, a
written designation of a beneficiary who is to receive any Shares or cash under
this Plan in the event of such Participant's death.  If a Participant's death
occurs subsequent to the end of an Election Period but prior to the delivery to
him or her of any Shares deliverable under the terms of this Plan, such Shares
and any remaining balance of cash shall be delivered to such beneficiary (or
such other person as set forth in Section 13(b)) as soon as administratively
practicable after the Company receives notice of such

                                       3
<PAGE>

Participant's death and the Participant's Option shall terminate. If a
Participant's death occurs at any other time, the balance of such Participant's
contributions shall be paid to such beneficiary (or such other person as set
forth in Section 13(b)) in cash as soon as administratively practicable after
the Company receives notice of such Participant's death and such Participant's
Option shall terminate. If a Participant is married and the designated
beneficiary is not his or her spouse, spousal consent shall be required for such
designation to be effective.

     (b) Beneficiary designations may be changed by the Participant (and his or
her spouse, if required) at any time on forms provided and in the manner
prescribed by the Committee.  If a Participant dies with no validly designated
beneficiary under this Plan who is living at the time of such Participant's
death, then the Participant's surviving spouse, if any, shall be deemed to be
the beneficiary.  If a Participant dies without a surviving spouse and with no
validly designated beneficiary under this Plan who is living at the time of such
Participant's death, the Company shall deliver all Shares and/or cash payable
pursuant to the terms hereof to the executor or administrator of the estate of
the Participant, or if no such executor or administrator has been appointed, the
Company, in its discretion, may deliver such Shares and/or cash to any one or
more dependents or relatives of the Participant, or if no dependent or relative
is known to the Company, then to such other person as the Committee deems
appropriate.

     14. Rights as a Stockholder.

     No Participant shall have any rights as a stockholder as to Shares being
purchased during any six month Election Period until after the end of such six
month Election Period when the Common Stock has actually been issued to the
Participant.  No adjustment shall be made or additional amount paid as a result
of dividends or other rights for which the record date is prior to the date of
such issuance.

     15. Listing, Registration and Qualification of Shares.

     The issuance of Shares under this Plan shall be subject to applicable
securities and other laws, including listing of the Shares on all stock
exchanges on which the Shares may be, from time to time, listed and the
registration of the Shares and Options under the Securities Act of 1933.

     16. Term of the Plan.

     The term of the Plan shall be for a period commencing on March 1, 1989 and
ending on March 31, 2009.

     17. Amendments.

     (a) The Board may terminate the Plan, in whole or in part, may suspend the
Plan, in whole or in part, from time to time and may amend the Plan from time to
time, including the adoption of amendments deemed necessary or desirable to
qualify the Plan under the laws of various countries (including tax laws) and
under rules and regulations promulgated by the Securities and Exchange
Commission (the "SEC") with respect to employees who are subject to the
provisions of Section 16 of the 1934 Act, or to correct any defect or supply an
omission or reconcile any inconsistency in the Plan or in any Option granted
thereunder, without the approval of the stockholders of the Company; provided,
however, that no action shall be taken without the approval of the stockholders
of the Company to increase the number of Shares of Stock on which Options may be
granted, or materially increase the benefits accruing to participants under the
Plan, or materially modify the requirements as to eligibility for participation
in the Plan, or withdraw administration from the Committee, or permit any person
while a member of the Committee to be eligible to receive, other than pursuant
to a non-discretionary formula plan, a grant or award of a stock option, a stock
appreciation right or other equity security of the Company.  Without limiting
the foregoing, the Committee may make amendments or adopt rules and procedures
applicable or inapplicable only to Participants who are subject to Section 16 of
the 1934 Act.

     (b) No amendment or termination or modification of the Plan shall in any
manner affect any Option theretofore granted without the consent of the
optionee, except that the Committee may amend or modify the Plan in a manner
that does affect Options theretofore granted upon a finding by the Committee
that such amendment or modification is in the best interest of holders of
outstanding Options affected thereby.

     (c) This Plan is intended to comply with all applicable requirements of
Rule 16b-3 or its successors under the 1934 Act, insofar as participants subject
to Section 16 of that Act are concerned.  To the extent any provision of the
Plan does not so comply, and cannot for any reason be amended by the Board, the
provision shall, to the extent permitted by law and deemed advisable by the
Committee, be deemed null and void with respect to such participants.

                                       4
<PAGE>

     18. Adjustments for Changes in Common Stock.

     (a) In the event of any stock split, stock dividend, recapitalization,
merger, consolidation, reorganization or other similar event, the Board shall
make appropriate and proportionate adjustments, including the substitution and
issuance of securities of any successor corporation for the Shares of the
Company to be issued under the Plan, to the maximum number of Shares subject to
the Plan, and the price per share subject to outstanding Options.

     (b) If the Company is acquired by merger or sale of all or substantially
all of the Company's assets or outstanding voting stock, then all outstanding
Options under the Plan will automatically be exercised immediately prior to the
effective date of such acquisition.  The exercise price in such event shall be
equal to 90% of the lower of (i) the fair market value per share of the Common
Stock on the first day of the Election Period in which such acquisition occurs
and (ii) the fair market value per share of the Common Stock immediately prior
to the effective date of such acquisition.

     19. Miscellaneous.

     This Plan is subject to all of the requirements of Section 423 of the Code
and the regulations thereunder.

     This Plan shall not confer any right on an employee to continue in the
employment of the Company or any subsidiary or division of the Company.

     The Company shall not be obligated to issue any Shares under the Plan
unless and until there has been compliance with such laws and regulations as the
Company deems applicable.

                                       5