<PAGE>

                                                                   EXHIBIT 10.3

                            SECOND AMENDMENT TO THE
                       MANTECH INTERNATIONAL CORPORATION
                         EMPLOYEE STOCK OWNERSHIP PLAN

     SECOND AMENDMENT to the ManTech International Corporation Employee Stock
Ownership Plan (the "Plan") by ManTech International Corporation (the
"Company").

     The Company maintains the Plan, effective as of January 1, 1999. The
Company has the power to amend the Plan and now wishes to do so.

     This Amendment of the Plan is adopted to reflect certain provisions of the
Economic Growth and Tax Relief Reconciliation Act of 2001 ("EGTRRA"). This
Amendment is intended as good faith compliance with the requirements of EGTRRA
and is to be construed in accordance with EGTRRA and the guidance issued
thereunder. Except as otherwise provided, this Amendment shall be effective as
of the first day of the first Plan Year beginning after December 31, 2001. This
amendment shall supersede the provisions of the Plan to the extent those
provisions are inconsistent with the provisions of this Amendment.

     NOW THEREFORE, the Plan is amended as follows:

I.   Effective January 1, 2002, Section 1.11 of the Plan is amended by adding
the following paragraph to the end thereof:

     "Increase in Compensation Limit. The annual compensation for each
     Participant taken into account in determining allocations for any Plan Year
     beginning after December 31, 2001, shall not exceed $200,000, as adjusted
     for cost-of-living increases in accordance with Code Section 401(a)(17)(B).
     Annual compensation means compensation during the Plan Year or such other
     consecutive 12-month period over which compensation is otherwise determined
     under the Plan (the determination period). The cost-of-living adjustment in
     effect for a calendar year applies to annual compensation for the
     determination period that begins with or within such calendar year."

<PAGE>

II.  Section 3.4 of the Plan is amended by adding the following paragraph after
the first paragraph thereof:

     "Limitations on Contributions. This paragraph shall be effective for
     Limitation Years beginning after December 31, 2001. The annual addition
     that may be contributed or allocated to a Participant's account under the
     Plan for any Limitation Year shall not exceed the lesser of: (a) $40,000,
     as adjusted for increases in the cost-of-living under Code Section 415(d),
     or (b) 100 percent of the Participant's compensation, within the meaning of
     Code Section 415(c)(3), for the limitation Year. The compensation referred
     to in (b) shall not apply to any contribution for medical benefits after
     separation from service (within the meaning of Code Section 401 (h) or
     419A(f)(2)) which is otherwise treated as an annual addition."

III. The Plan is amended by adding a new Section 7.3 as follows:

     "7.3"   Distribution upon Severance from Employment.

             (a)   Effective date. This Section 7.3 shall apply for
     distributions and severances from employment occurring after December 31,
     2001.

             (b)   New distributable event. A Participant's elective deferrals,
     qualified nonelective contributions, qualified matching contributions, and
     earnings attributable to these contributions shall be distrbuted on account
     of the Participant's severance from employment. However, such a
     distribution shall be subject to the other provisions of the Plan regarding
     distributions, other than provisions that require a separation from service
     before such amounts may be distributed."

IV.  Section 8.1(b)(i) of the Plan is amended in its entirety to read as
follows:

     "(i)    (A)   If the value of the vested balance in such Account as of such
     Valuation Date does not exceed, nor at any other time exceeded, $5,000, the
     Participant's vested balance in his or her Account shall be distributed in
     cash to him or her in the form of a single lump sum payment, as soon as
     practicable, but in no event later than that last day of the plan Year
     following the Plan Year in which the Participant terminates employment.

             (B)   Rollovers Disregarded in Involuntary Cashouts.

                   (1)   Applicability and effective date. This subsection (B)
     shall apply to Plan distributions made after December 31, 2001.

                   (2)   Rollovers disregarded in determining value of account
     balance for involuntary distributions. For purposes of the Plan, the value
     of a Participant's nonforfeitable account balance shall be determined
     without regard to that portion of the

                                       2

<PAGE>

          account balance that is attributable to rollover contributions (and
          earnings allocable thereto) within the meaning of Code Sections
          402(c), 403(a)(4), 403(b)(8), 408(d)(3)(A)(ii), and 457(e)(16). If the
          value of the Participant's nonforfeitable account balance as so
          determined is $5,000 or less, the Plan shall immediately distribute
          the Participant's entire nonforfeitable account balance."

     V.   Section 8.5 of the Plan is amended by adding a new subsection (e) as
          follows:

          "(e)  Direct Rollovers of Plan Distributions.

                (i)   Effective date. The subsection (e) shall apply to
          distributions made after December 31, 2001.

                (ii)  Modification of definition of eligible retirement plan.
          For purposes of the direct rollover provisions in this Section 6.14 of
          the Plan, an eligible retirement plan shall also mean and annuity
          contract described in Code Section 403(b) and an eligible plan under
          Code Section 457(b) which is maintained by a state, political
          subdivision of a state, or any agency or instrumentality of a state or
          political subdivision of a state and which agrees to separately
          account for amounts transferred into such plan from this Plan. The
          definition of eligible retirement plan shall also apply in the case of
          a distribution to a surviving spouse, or to a spouse or former spouse
          who is the alternate payee under a qualified domestic relation order,
          as defined in Code Section 414(p).

                (iii) Modification of definition of eligible rollover
          distribution to exclude hardship distributions. For purposes of the
          direct rollover provision in this Section 6.14 of the Plan, any amount
          that is distributed on account of hardship shall not be an eligible
          rollover distribution and the distributee may not elect to have any
          portion of such a distribution paid directly to an eligible retirement
          plan."

     VI.  The Plan is amended by adding a new Section 13.4 as follows:

          "13.4 Modification of Top-Heavy Rules

                (a)   Effective date. This Section 13.4 shall apply for purposes
          of determining whether the Plan is a top-heavy plan under Code Section
          416(g) for Plan Years beginning after December 31, 2001, and whether
          the Plan satisfies the minimum benefits requirements of Code Section
          416(c) for such years. This Section 13.4 amends Sections 13.2 and 13.3
          of the Plan.

                (b)   Determination of top heavy status.

                  (i) Key employee. Key employee means any employee or former
          employee (including any deceased employee) who at any time during the
          Plan Year that includes the determination date was an officer of the
          employer having annual compensation

                                       3

<PAGE>

      greater than $130,000 (as adjusted under Code Section 416(i)(1) for Plan
      Years beginning after December 31, 2002), a 5-percent owner of the
      employer, or a 1-percent owner of the employer having annual compensation
      of more than $150,000. For this purpose, annual compensation means
      compensation within the meaning of Code Section 415(c)(3). The
      determination of who is a key employee will be made in accordance with
      Code Section 416(i)(1) and the applicable regulations and other guidance
      of general applicability issued thereunder.

             (ii)  Determination of present values and amounts. This subsection
      (ii) shall apply for purposes of determining the present values of
      accrued benefits and the amounts of account balances of employees as of
      the determination date.

                  (A) Distributions during year ending on the determination
      date. The present values of accrued benefits and the amounts of account
      balances of an employee as of the determination date shall be increased by
      the distributions made with respect to the employee under the Plan and any
      plan aggregate with the Plan under Code Section 416(g)(2) during the
      1-year period ending on the determination date. The preceding sentence
      shall also apply to distributions under a termination plan which, had it
      not been terminated, would have been aggregated with the plan under Code
      Section 416(g)(2)(A)(i). In the case of a distribution made for a reason
      other than separation from service, death, or disability, this provision
      shall be applied by substituting "5-year period" for "1-year period."

                  (B) Employees not performing services during year ending on
      the determination date. The accrued benefits and accounts of any
      individual who has not performed services for the employer during the
      1-year period ending on the determination date shall not be taken into
      account.

          (c)     Minimum benefits.

             (i)   Matching contributions. Employer matching contributions under
      the ManTech International 401(k) Plan shall be taken into account for
      purposes of satisfying the minimum contribution requirements of Code
      Section 416(c)(2) and the Plan. Employer matching contributions that are
      used to satisfy the minimum contribution requirements shall be treated as
      matching contributions for purposes of the actual contribution percentage
      test and other requirements of Code Section 401(m).

             (ii)  Contributions under other plans. To the extent minimum
      contribution has not already been met by the Employer Contribution for the
      Plan Year, the minimum contribution required under Code Section 416(c)(2)
      shall be provided under the ManTech International 401(k) Plan.

VII.  In all respects not amended, the Plan is hereby ratified and confirmed.

                                 *  *  *  *  *

                                       4

<PAGE>

     To record adoption of the Amendment as set forth above, the Company has
caused this document to be signed on this 15/th/ day of December, 2001.


                                        ManTech International Corporation

                                        By: /s/ JOHN A. MOORE, JR.
                                            -----------------------------------

                                        5