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                                                                    EXHIBIT 10.4

                      ADVANCED COMMUNICATION SYSTEMS, INC.
                          EMPLOYEE STOCK PURCHASE PLAN



                                    ARTICLE I
                                     PURPOSE

       1.01.  PURPOSE. The Advanced Communication Systems, Inc. Employee Stock
Purchase Plan is intended to provide a method whereby employees of Advanced
Communication Systems, Inc. (the "Company") and its subsidiary corporations will
have an opportunity to acquire a proprietary interest in the Company through the
purchase of shares of the Common Stock of the Company. It is the intention of
the Company to have the Plan qualify as an "employee stock purchase plan" under
Section 423 of the Internal Revenue Code of 1986, as amended (the "Code"). The
provisions of the Plan shall be construed so as to extend and limit
participation in a manner consistent with the requirements of that section of
the Code.

                                   ARTICLE II
                                   DEFINITIONS

       2.01   BASE PAY. "Base Pay" means regular straight-time earnings
excluding payments for overtime, shift premium, bonuses and other special
payments, commissions and other marketing incentive payments.

       2.02   BOARD. "Board of Directors" or "Board" means the Board of
Directors of the Company.

       2.03   COMMITTEE. "Committee" means the individuals described in Article
XI.

       2.04   COMMON STOCK. "Common Stock" means the common stock of the
Company.

       2.05   DESIGNATED SUBSIDIARY CORPORATION. "Designated Subsidiary
Corporation" means a Subsidiary Corporation which is designated by the Company's
Board of Directors to participate in the Plan.

       2.06   EMPLOYEE. "Employee" means any person who is employed by the
Company or a Designated Subsidiary Corporation.

       2.07   SUBSIDIARY CORPORATION. "Subsidiary Corporation" means any present
or future corporation which would be a "subsidiary corporation" of the Company
as that term is defined in Section 424 of the Code.


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                                   ARTICLE III
                          ELIGIBILITY AND PARTICIPATION

       3.01   INITIAL ELIGIBILITY. All Employees are eligible to participate
hereunder, commencing on any Commencement Date.

       3.02   COMMENCEMENT OF PARTICIPATION. An eligible Employee may become a
participant by completing an authorization for payroll deduction on the form
provided by the Company and filing it with the office of the Human Resources
Director of the Company prior to the Commencement Date for the Offering (as such
terms are defined below) or, in the case of the first Offering, prior to such
other enrollment deadline established by the Committee. Payroll deductions for a
participant shall commence on the applicable Commencement Date when his
authorization for a payroll deduction becomes effective and shall end on the
Exercise Date of the Offering to which such authorization is applicable unless
sooner terminated by the participant as provided in Article VIII.

       3.03   RESTRICTIONS ON PARTICIPATION. Notwithstanding any provision of
the Plan to the contrary, no Employee shall be granted an option to participate
in the Plan:

              (a)    if, immediately after the grant, such Employee would own
stock, and/or hold outstanding options to purchase stock, possessing 5% or more
of the total combined voting power or value of all classes of stock of the
Company or any Subsidiary Corporation. (For purposes of this paragraph, the
rules of Section 424(d) of the Code shall apply in determining stock ownership
of any Employee); or

              (b)    which permits his rights to purchase stock under all
employee stock purchase plans of the Company and its Subsidiary Corporations to
accrue at a rate which exceeds $25,000 in fair market value of the stock
(determined at the time such option is granted) for each calendar year in which
such option is outstanding.

       3.04   LEAVE OF ABSENCE. For purposes of participation in the Plan, a
person on leave of absence shall be deemed to be an Employee for the first 90
days of such leave of absence and such Employee's employment shall be deemed to
have terminated at the close of business on the 90th day of such leave of
absence unless such Employee shall have returned to regular full-time or
part-time employment (as the case may be) prior to the close of business on such
90th day. Termination by the Company of any Employee's leave of absence, other
than termination of such leave of absence on return to full time or part time
employment, shall terminate an Employee's employment for all purposes of the
Plan and shall terminate such Employee's participation in the Plan and right to
exercise any option.


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                                   ARTICLE IV
                                    OFFERINGS

       4.01   QUARTERLY OFFERING PERIODS.

              (a)    Offering Periods. The Plan will be implemented by Offerings
in consecutive Offering Periods, each constituting a calendar quarter. Such
Offering Periods shall continue until the termination of the Plan in accordance
with Section 12.05. The first such Offering Period shall begin on the later of
(i) April 1, 1998, or (ii) the effective date of the registration statement
filed by the Company for the Plan with the Securities and Exchange Commission.

              (b)    Commencement Date. The Commencement Date is the first
business day of an Offering Period.

              (c)    Exercise Date. The Exercise Date is the last business day
of an Offering Period.

       4.02   REVISED OFFERING PERIODS. In the discretion of the Committee,
quarterly Offering Periods may be divided into monthly Offering Periods or
combined into annual or semi-annual Offering Periods. The maximum number of
shares available during an Offering Period under Section 10.01 shall be adjusted
appropriately.

                                    ARTICLE V
                               PAYROLL DEDUCTIONS

       5.01   AMOUNT OF DEDUCTION. At the time a participant files his
authorization for payroll deduction, he shall elect to have after-tax deductions
made from his pay on each payday during the Offering Period at the rate of 1, 2,
3, 4, 5, 6, 7, 8, 9 or 10% of his base pay in effect at any such payday, subject
to a minimum of $20 per month.

       5.02   PARTICIPANT'S ACCOUNT. All payroll deductions made for a
participant shall be credited to his account under the Plan. A participant may
not make any separate cash payment into such account except when on leave of
absence and then only as provided in Section 5.04.

       5.03   CHANGES IN PAYROLL DEDUCTIONS. A participant may discontinue his
participation in the Plan as provided in Article VIII, but no other change can
be made during an Offering and, specifically, a participant may not alter the
amount of his payroll deductions for that Offering. The payroll deduction form
may provide that it shall continue from Offering Period to Offering Period
unless changed by a participant before the beginning of a subsequent Offering
Period.


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       5.04   LEAVE OF ABSENCE. If a participant goes on a leave of absence,
such participant shall have the right to elect: (a) to withdraw the balance in
his or her account pursuant to Section 7.02, (b) to discontinue contributions to
the Plan but remain a participant in the Plan, or (c) remain a participant in
the Plan during such leave of absence, authorizing deductions to be made from
payments by the Company or its Subsidiary Corporations to the participant during
such leave of absence and undertaking to make cash payments to the Plan at the
end of each payroll period to the extent that amounts payable by the Company and
its Subsidiary Corporations to such participant are insufficient to meet such
participant's authorized Plan deductions.

                                   ARTICLE VI
                               GRANTING OF OPTION

       6.01   NUMBER OF OPTION SHARES. On the Commencement Date of each
Offering, subject to the maximum in Section 10.01, a participating Employee
shall be deemed to have been granted a qualified option to purchase on the
Exercise Date of such Offering Period (at the Purchase Price in Section 6.02)
the number of shares of the Company's Common Stock determined by dividing such
Employee's after-tax payroll deductions accumulated during such Offering Period
and retained in the participant's account as of the Exercise Date by the
applicable Purchase Price.

       6.02   PURCHASE PRICE. The Purchase Price of Common Stock purchased with
payroll deductions made during an Offering Period for a participant therein
shall be the lower of: (a) 90% of the Fair Market Value of the stock on the
Commencement Date, or (b) 90% of the Fair Market Value of the stock on the
Exercise Date. The Fair Market Value of the stock for this purpose is the
closing price of the stock on the NASDAQ National Market System on that date, or
(in the event the stock was not traded on such date) the nearest prior business
day on which trading of the Company's Common Stock occurred. If the Common Stock
is not listed on the NASDAQ National Market System, Fair Market Value shall be
similarly determined with reference to the principal U.S. Stock Exchange on
which the Common Stock is listed. If the Company's Common Stock is not admitted
to trading on the NASDAQ National Market System or other U.S. Stock Exchange on
any of the aforesaid dates for which closing prices of the stock are to be
determined, then reference shall be made to the fair market value of the stock
on that date, as determined on such basis as shall be established or specified
for the purpose by the Committee.

                                   ARTICLE VII
                               EXERCISE OF OPTION

       7.01   AUTOMATIC EXERCISE. Unless a participant gives written notice to
the Company as hereinafter provided, his option for the purchase of stock with
payroll deductions made during any Offering will be deemed to have been
exercised automatically on the Exercise Date applicable to such Offering, for
the purchase of the number of shares of Common Stock which the accumulated
payroll deductions in his


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account at that time will purchase at the applicable Purchase Price, subject to
the maximum stated in Section 10.01. Any excess payroll deductions in his
account at that time not utilized to purchase Common Stock will be refunded to
him.

       7.02   WITHDRAWAL OF ACCOUNT. By written notice to the Human Resources
Director of the Company, at any time prior to the Exercise Date applicable to
any Offering, a participant may elect to withdraw all of the accumulated payroll
deductions in his account at such time.

       7.03   TRANSFERABILITY OF OPTION. During a participant's lifetime,
options held by such participant shall be exercisable only by that participant.

       7.04   DELIVERY OF STOCK. As promptly as practicable after the Exercise
Date of each Offering, the Company will arrange for delivery of the stock
purchased upon exercise of his option to an account established for the
participant at a brokerage firm designated by the Company.

       7.05   DIVIDENDS. Any cash dividends paid on Company Common Stock held in
a participant's account at a designated brokerage firm shall be automatically
reinvested in Company Common Stock as soon as administratively practicable by
purchases on the open market at prevailing market prices. Such purchases shall
not count towards the limits in Section 10.01.

                                  ARTICLE VIII
                                   WITHDRAWAL

       8.01   IN GENERAL. As indicated in Section 7.02, a participant may
withdraw payroll deductions credited to his account under the Plan at any time
by giving written notice to the Human Resources Director of the Company. All of
the participant's payroll deductions credited to his account will be paid to him
promptly after receipt of his notice of withdrawal, and no further payroll
deductions will be made from his pay during such Offering. The Company may, at
its option, treat any attempt to borrow by an Employee on the security of his
accumulated payroll deductions as an election, under Section 7.02, to withdraw
such deductions.

       8.02   EFFECT ON SUBSEQUENT PARTICIPATION. A participant's withdrawal
from any Offering will not have any effect upon his eligibility to participate
in any succeeding Offering or in any similar plan which may hereafter be adopted
by the Company.

       8.03   TERMINATION OF EMPLOYMENT. Upon termination of the participant's
employment for any reason, including retirement or death (but excluding
continuation of a leave of absence for a period beyond 90 days), the payroll
deductions credited to his account will be returned to him, or, in the case of
his death, to the person or persons entitled thereto under Section 12.01.


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                                   ARTICLE IX
                                    INTEREST

       9.01   NO PAYMENT OF INTEREST. No interest will be paid or allowed on any
money paid into the Plan or credited to the account of any participating
Employee.

                                    ARTICLE X
                                      STOCK

       10.01  SHARES SUBJECT TO PLAN. The stock subject to the Plan shall be
shares of the Company's Common Stock, which may be (i) authorized but unissued
shares, (ii) treasury shares and/or (iii) shares purchased on the open market by
a broker designated by the Company. The maximum number of shares of Common Stock
which shall be issued under the Plan, subject to adjustment upon changes in
capitalization of the Company as provided in Section 12.04, shall be Eighty
Thousand (80,000) shares in each Offering plus in each Offering all unissued
shares from prior Offerings, whether offered or not, not to exceed Three Hundred
Twenty-Five Thousand (325,000) shares for all Offerings. No participant may
purchase more than Five Hundred (500) shares in any one Offering. If the total
number of shares for which options are exercised on any Exercise Date in
accordance with Article VI exceeds the maximum number of shares for the
applicable offering, the Company shall make a pro rata allocation of the shares
available for delivery and distribution in as nearly a uniform manner as shall
be practicable and as it shall determine to be equitable, and the balance of
payroll deductions credited to the account of each participant under the Plan
shall be returned to him as promptly as possible.

       10.02  PARTICIPANT'S INTEREST IN OPTION STOCK. The participant will have
no interest in stock covered by his option until such option has been exercised.

       10.03  ISSUANCE OF STOCK. Stock purchased under the Plan will be issued
in a street name and held at a brokerage firm designated by the Company, which
brokerage firm shall maintain an account for each participant reflecting his or
her allocable shares of the Common Stock and any earnings thereon. A participant
may at any time request such brokerage firm to issue a certificate for the
shares of Common Stock allocated to the participant's account.

       10.04  RESTRICTIONS ON EXERCISE. The Board of Directors may, in its
discretion, require as conditions to the exercise of any option that the shares
of Common Stock reserved for issuance upon the exercise of the option shall have
been duly listed, upon official notice of issuance, upon a stock exchange, and
that either:

              (a)    a registration statement under the Securities Act of 1933,
as amended, with respect to said shares shall be effective, or


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              (b)    the participant shall have represented at the time of
purchase, in form and substance satisfactory to the Company, that it is his
intention to purchase the shares for investment and not for resale or
distribution.

                                   ARTICLE XI
                                 ADMINISTRATION

       11.01  APPOINTMENT OF COMMITTEE. The Board of Directors shall appoint a
committee (the "Committee") to administer the Plan, which shall consist of
either (a) the full Board of Directors or (b) no fewer than two members of the
Board of Directors.

       11.02  AUTHORITY OF COMMITTEE. Subject to the express provisions of the
Plan, the Committee shall have plenary authority in its discretion to interpret
and construe any and all provisions of the Plan, to adopt rules and regulations
for administering the Plan, and to make all other determinations deemed
necessary or advisable for administering the Plan. The Committee's determination
on the foregoing matters shall be conclusive.

       11.03  RULES GOVERNING THE ADMINISTRATION OF THE COMMITTEE. The Board of
Directors may from time to time appoint members of the Committee in substitution
for or in addition to members previously appointed and may fill vacancies,
however caused, in the Committee. The Committee may select one of its members as
its Chairman and shall hold its meetings at such times and places as it shall
deem advisable and may hold telephonic meetings. A majority of its members shall
constitute a quorum. All determinations of the Committee shall be made by a
majority of its members. The Committee may correct any defect or omission or
reconcile any inconsistency in the Plan, in the manner and to the extent it
shall deem desirable. Any decision or determination reduced to writing and
signed by a majority of the members of the Committee shall be as fully effective
as if it had been made by a majority vote at a meeting duly called and held. The
Committee may appoint a secretary and shall make such rules and regulations for
the conduct of its business as it shall deem advisable.

       11.04  LIMITED LIABILITY; INDEMNIFICATION. To the maximum extent
permitted by Virginia law, neither the Company, Board or Committee nor any of
its members shall be liable for any action or determination made in good faith
with respect to this Plan. In addition to such other rights of indemnification
that they may have, the members of the Board and Committee shall be indemnified
by the Company to the maximum extent permitted by Virginia law against any and
all liabilities and expenses incurred in connection with their service in
connection with the Plan in such capacity.

                                   ARTICLE XII
                                  MISCELLANEOUS

       12.01  DESIGNATION OF BENEFICIARY. A participant may file a written
designation of a beneficiary who is to receive any cash which is in the
participant's account at the time of the participant's death. Such designation
of beneficiary may be changed by the


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participant at any time by written notice to the Human Resources Director of the
Company. Upon the death of a participant and upon receipt by the Company of
proof of identity and existence at the participant's death of a beneficiary
validly designated by him under the Plan, the Company shall deliver such cash to
such beneficiary. In the event of the death of a participant and in the absence
of a beneficiary validly designated under the Plan who is living at the time of
such participant's death, the Company shall deliver such cash to the executor or
administrator of the estate of the participant, or if no such executor or
administrator has been appointed (to the knowledge of the Company), the Company,
in its discretion, may deliver such cash to the spouse or to any one or more
dependents of the participant as the Company may designate. No beneficiary
shall, prior to the death of the participant by whom he has been designated,
acquire any interest in the account of the participant under the Plan.

       12.02  TRANSFERABILITY. Neither payroll deductions credited to a
participant's account nor any rights with regard to the exercise of an option or
to receive stock under the Plan may be assigned, transferred, pledged, or
otherwise disposed of in any way by the participant other than by will or the
laws of descent and distribution. Any such attempted assignment, transfer,
pledge or other disposition shall be without effect, except that the Company may
treat such act as an election to withdraw funds in accordance with Section 7.02.

       12.03  USE OF FUNDS. All payroll deductions received or held by the
Company under this Plan may be used by the Company for any corporate purpose and
the Company shall not be obligated to segregate such payroll deductions.

       12.04  ADJUSTMENT UPON CHANGES IN CAPITALIZATION.

              (a)    If, while any options are outstanding, the outstanding
shares of Common Stock of the Company have increased, decreased, changed into,
or been exchanged for a different number or kind of shares or securities of the
Company through reorganization, merger, recapitalization, reclassification,
stock split, reverse stock split or similar transaction, appropriate and
proportionate adjustments may be made by the Committee in the number and/or kind
of shares which are subject to purchase under outstanding options and on the
option exercise price or prices applicable to such outstanding options. In
addition, in any such event, the maximum number and/or kind of shares which may
be offered in the Offerings described in Articles IV and Section 10.01 hereof
shall also be proportionately adjusted. No adjustments shall be made for stock
dividends. For the purposes of this Paragraph, any distribution of shares to
shareholders in an amount aggregating 20% or more of the outstanding shares
shall be deemed a stock split and any distributions of shares aggregating less
than 20% of the outstanding shares shall be deemed a stock dividend.

              (b)    Upon the dissolution or liquidation of the Company, or upon
a reorganization, merger or consolidation of the Company with one or more
corporations as a result of which the Company is not the surviving corporation,
or upon a sale of


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substantially all of the property or stock of the Company to another
corporation, the Committee shall take such action as it deems appropriate and
equitable, which action may include, without limitation, one of the following:
(i) refund of payroll deductions for such Offering Period; (ii) shortening of
the Offering Period or (iii) providing that the holder of each option then
outstanding under the Plan will thereafter be entitled to receive at the next
Exercise Date upon the exercise of such option for each share as to which such
option shall be exercised, as nearly as reasonably may be determined, the cash,
securities and/or property which a holder of one share of the Common Stock was
entitled to receive upon and at the time of such transaction. In the event the
Plan is continued after such event, the Board of Directors shall take such steps
in connection with such transactions as the Board shall deem necessary to assure
that the provisions of this Section 12.04 shall thereafter be applicable, as
nearly as reasonably may be determined, in relation to the said cash, securities
and/or property as to which such holder of such option might thereafter be
entitled to receive.

       12.05  AMENDMENT AND TERMINATION.

              (a)    Action by Board. The Board of Directors shall have complete
power and authority to terminate or amend the Plan; provided, however, that the
Board of Directors shall not, without the approval of the stockholders of the
Company (i) amend the Plan in a manner to cause the Plan to fail to meet the
requirements of Code Section 423 or fail to comply with Rule 16b-3 of the
Securities and Exchange Commission, or (ii) increase the maximum number of
shares which may be issued under the Plan or under any Offering (except pursuant
to Sections 4.02 and 12.04). Upon termination of the Plan during an Offering
Period, at the discretion of the Committee, cash balances in participants
accounts may be refunded or the Exercise Date may be accelerated. Except as
provided above, no termination, modification, or amendment of the Plan may,
without the consent of an Employee then having an option under the Plan to
purchase stock, adversely affect the rights of such Employee under such option.

              (b)    Automatic Termination. The Plan shall automatically
terminate on the earlier of March 31, 2008, or the issuance of the maximum
number of shares available under the Plan pursuant to Section 10.01.

       12.06  TAX WITHHOLDING. At the time an option is exercised or at the time
some or all of the Company's Common Stock issued under the Plan is disposed of,
the participant must make adequate provision for the Company's federal, state,
or other tax withholding obligations, if any, which arise upon the exercise of
the option or the disposition of the Common Stock. At any time, the Company may,
but shall not be obligated to, withhold from the participant's compensation the
amount necessary for the Company to meet applicable withholding obligations.

       12.07  DISQUALIFYING DISPOSITION. The Committee may require that a
participant notify the Company of any disposition of shares of Common Stock
purchased under the


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Plan within a period of two (2) years subsequent to the respective Commencement
Date or one (1) year from the Exercise Date.

       12.08  EFFECTIVE DATE. The Plan shall become effective as of April 1,
1998, subject to approval by the holders of the majority of the Common Stock
present and represented at a special or annual meeting of the shareholders held
on or before March 31, 1999. If the Plan is not so approved, the Plan shall be
discontinued, any options which had been issued shall be considered nonqualified
options and any payroll deductions then held by the Company shall be refunded to
the respective Employees.

       12.09  NO EMPLOYMENT RIGHTS. The Plan does not, directly or indirectly,
create in any Employee or class of Employees any right with respect to
continuation of employment by the Company, and it shall not be deemed to
interfere in any way with the Company's right to terminate, or otherwise modify,
an Employee's employment at any time.

       12.10  EXCLUSION FROM RETIREMENT AND FRINGE BENEFIT COMPUTATION. No
portion of the award of options under this Plan, or the proceeds from the sale
of stock purchased under the Plan, shall be taken into account as "wages,"
"salary" or "compensation" for any purpose, whether in determining eligibility,
benefits or otherwise, under (i) any pension, retirement, profit sharing or
other qualified or non-qualified plan of deferred compensation, (ii) any
employee welfare or fringe benefit plan including, but not limited to, group
insurance, hospitalization, medical, and disability, or (iii) any form of
extraordinary pay including, but not limited to, bonuses, sick pay and vacation
pay.

       12.11  EFFECT OF PLAN. The provisions of the Plan shall, in accordance
with its terms, be binding upon, and inure to the benefit of, all successors of
each Employee participating in the Plan, including, without limitation, such
Employee's estate and the executors, administrators or trustees thereof, heirs
and legatees, and any receiver, trustee in bankruptcy or representative of
creditors of such Employee.

       12.12  EXPENSES. Expenses of administering the Plan shall be borne by the
Company except that brokerage expenses incurred in connection with the purchase
of shares shall be included as part of the cost of the shares to participating
Employees.

       12.13  GOVERNING LAW. The law of the Commonwealth of Virginia will govern
all matters relating to this Plan except to the extent it is superseded by the
laws of the United States.


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