Exhibit 10.1

                           PURCHASE AND SALE AGREEMENT
         THIS PURCHASE AND SALE AGREEMENT (this "Agreement") is made October 21,
2003 by and between GP Strategies Corporation, a Delaware corporation
("Purchaser"), and ManTech International Corporation, a Delaware corporation
("Seller").

         The parties agree as follows:

         1. Purchase and Sale. Purchaser agrees to purchase from Seller, and
Seller agrees to sell to Purchaser, (a) 3,426,699 shares (the "GSE Shares") of
common stock of GSE Systems, Inc., a Delaware corporation ("GSE"), and (b) a
subordinated promissory note (the "GSE Note", together with the GSE Shares, the
"GSE Securities") of GSE payable to the order of Seller in the original
principal amount of $1,000,000, of which $650,000 shall be outstanding when it
is sold to Purchaser, for an aggregate purchase price (the "Purchase Price")
equal to the sum of $5,250,955.

         2. Payment of Purchase Price.Purchaser shall pay the Purchase Price by
delivery at the Closing (as defined below) of a promissory note of Purchaser
substantially in the form attached as Exhibit A (the "GPX Note").

         3. Purchaser's Representations. As a material inducement to Seller to
enter into and perform its obligations under this Agreement, Purchaser
represents and warrants to Seller as follows:

                  (a) Organization and Good Standing. Purchaser is a corporation
         duly organized, validly existing and in good standing under the laws of
         the State of Delaware, and is duly qualified to do business and is in
         good standing in each jurisdiction in which its ownership or use of its
         assets requires such qualification.

                  (b) Authorization. The execution and delivery of this
         Agreement and the GPX Note, and the performance of the transactions
         contemplated hereby, (i) have been duly authorized and approved by all
         necessary corporate action of Purchaser, including, but not limited to,
         approval by the directors of Purchaser in accordance with Purchaser's
         governing documents, and (ii) do not and will not (A) conflict with, or
         violate any provision of, any law having applicability to Purchaser or
         any of its assets or any provision of the certificate of incorporation
         or bylaws of Purchaser, (B) subject to obtaining the consent of
         Purchaser's lenders, conflict with, or result in any breach of, or
         constitute a default under, any agreement to which Purchaser is a party
         or by which it or any of its assets may be bound, or (C) subject to
         obtaining the consent of Purchaser's lenders, result in or require the
         creation, imposition or acceleration of any indebtedness, or of any
         encumbrance of any nature upon, or with respect to, Purchaser or any of
         its assets now owned.

                  (c) Binding Obligation. This Agreement, the GPX Note and each
         document to be executed by Purchaser pursuant hereto constitute valid
         and binding obligations of Purchaser, enforceable in accordance with
         their terms, except to the extent that such enforcement may be limited



         by applicable bankruptcy, reorganization, insolvency, moratorium or
         other laws of general application relating to or affecting the
         enforcement of creditors' rights as from time to time in effect.

                  (d) Finders or Brokers. Purchaser is not party to any
         agreement with any agent, broker, investment banker or other third
         party, or in any way obligated to any agent, broker, investment banker
         or other third party, for any commissions or fees in connection with
         the origin, negotiation, execution or performance of this Agreement or
         any of the transactions contemplated herein.

                  (e) Investment Representations.

                                    (i) Purchaser is aware of the business
                  affairs and financial condition of GSE and has acquired
                  sufficient information about GSE to reach an informed and
                  knowledgeable decision to acquire the GSE Securities.
                  Purchaser is purchasing the GSE Securities for investment and
                  for Purchaser's own account only and not with a view to, or
                  for resale in connection with, any "distribution" thereof
                  within the meaning of the Securities Act of 1933, as amended
                  ("Securities Act").

                                    (ii) Purchaser understands that the GSE
                  Shares have not been registered under the Securities Act and
                  are being sold to Purchaser in reliance upon the exemption
                  from such registration provided by Section 4(1) of the
                  Securities Act. Purchaser hereby confirms that it has been
                  informed that the GSE Shares are restricted securities under
                  the Securities Act and may not be resold or transferred unless
                  the GSE Shares are first registered under the Federal
                  securities laws and any applicable state securities law or an
                  exemption from such registration is available.

                                    (iii) Purchaser further acknowledges and
                  understands that GSE is under no obligation to register under
                  the Securities Act the resale of the GSE Shares. Purchaser
                  understands that the certificate(s) evidencing the GSE Shares
                  will be imprinted with a legend substantially in the form as
                  set forth below which prohibits the transfer of the GSE Shares
                  unless the sale of such shares has been so registered or such
                  registration is not required in the opinion of counsel
                  satisfactory to the GSE.
                  "THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED

                  FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN CONNECTION WITH,
                  THE SALE OR DISTRIBUTION THEREOF. NO SUCH SALE OR DISPOSITION
                  MAY BE EFFECTED WITHOUT AN EFFECTIVE REGISTRATION STATEMENT
                  RELATED THERETO OR AN OPINION OF COUNSEL SATISFACTORY TO THE
                  COMPANY THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE
                  SECURITIES ACT OF 1933."



         4. Seller's Representations. As a material inducement to Purchaser to
enter into and perform its obligations under this Agreement, Seller represents
and warrants to Purchaser as follows:

                  (a) Organization and Good Standing. Seller is a corporation
         duly organized, validly existing and in good standing under the laws of
         the State of Delaware, and is duly qualified to do business and is in
         good standing in each jurisdiction in which its ownership or use of its
         assets requires such qualification.

                  (b) Authorization. The execution and delivery of this
         Agreement and the performance of the transactions contemplated hereby
         (i) have been duly authorized and approved by all necessary corporate
         action of Seller, including, but not limited to, approval by the
         directors of Seller in accordance with Seller's governing documents,
         and (ii) do not and will not (A) conflict with, or violate any
         provision of, any law having applicability to Seller or any of its
         assets or any provision of the certificate of incorporation or bylaws
         of Seller, (B) conflict with, or result in any breach of, or constitute
         a default under, the GSE Note or any agreement to which Seller is a
         party or by which it or any of its assets may be bound, or (C) result
         in or require the creation, imposition or acceleration of any
         indebtedness, or of any encumbrance of any nature upon, or with respect
         to, Seller or any assets now owned.

                  (c) Title. Seller beneficially owns and has the unrestricted
         right (other than as such right may be restricted by the Securities Act
         or any applicable state securities laws) to transfer the GSE
         Securities, subject to obtaining a lien release from Seller's lenders,
         which shall be obtained at or prior to Closing, free and clear of all
         liens, security interests, pledges, stockholder agreements, voting
         trusts, claims, charges and other encumbrances (collectively, "Liens").
         Upon completion of the Closing, Purchaser will be the legal and
         beneficial owner of the GSE Shares and GSE Note, free and clear of all
         Liens.
                  (d) Binding Obligation. This Agreement and each document to be
         executed by Seller pursuant hereto constitute a valid and binding
         obligation of Seller, enforceable in accordance with their terms except
         to the extent that such enforcement may be limited by applicable
         bankruptcy, reorganization, insolvency, moratorium or other laws of
         general application relating to or affecting the enforcement of
         creditors' rights as from time to time in effect.

                  (e) GSE Shares and GSE Note. Each of the GSE Shares is validly
         authorized, validly issued, fully paid, and nonassessable, and has not
         been issued and is not owned or held in violation of any preemptive
         right of stockholders. The GSE Note constitutes, and after its transfer
         to Purchaser will constitute, a valid and binding obligation of GSE,
         enforceable in accordance with its terms, except to the extent that
         such enforcement may be limited by (i) applicable bankruptcy,
         reorganization, insolvency, moratorium or other laws of general
         application relating to or affecting the enforcement of creditors'
         rights as from time to time in effect, (ii) any GSE lender approvals or
         requirements. The outstanding principal amount of the GSE Note
         immediately after the Closing will be $650,000.



                  (f) Finders or Brokers. Seller is not party to any agreement
         with any agent, broker, investment banker or other third party, or in
         any way obligated to any agent, broker, investment banker or other
         third party, for any commissions or fees in connection with the origin,
         negotiation, execution or performance of this Agreement or any of the
         transactions contemplated herein.

                  (g) Investment Representations.

                                    (i) Seller is aware of the business affairs
                  and financial condition of Purchaser and has acquired
                  sufficient information about Purchaser to reach an informed
                  and knowledgeable decision to acquire the GPX Note. Seller is
                  purchasing the GPX Note for investment and for Seller's own
                  account only and not with a view to, or for resale in
                  connection with, any "distribution" thereof within the meaning
                  of the Securities Act of 1933, as amended ("Securities Act").

                                   (ii) Seller understands that the GPX Note
                  has not been registered under the Securities Act and is being
                  sold to Seller in reliance upon the exemption from such
                  registration provided by Section 4(2) of the Securities Act.
                  Seller hereby confirms that it has been informed that the GPX
                  Note and the shares of common stock of Purchaser issuable upon
                  conversion of the GPX Note (the "GPX Shares") are restricted
                  securities under the Securities Act and may not be resold or
                  transferred unless the GPX Note and GPX Shares are first
                  registered under the Federal securities laws and any
                  applicable state securities laws or an exemption from such
                  registration is available.

                                    (iii) Seller further acknowledges and
                  understands that Purchaser is under no obligation to register
                  under the Securities Act the resale of the GPX Note or, except
                  as set forth in the GPX Note, the GPX Shares. Seller
                  understands that the GPX Note and the certificate(s)
                  evidencing the GPX Shares will be imprinted with a legend
                  substantially in the form as set forth below which prohibits
                  the transfer of the GPX Note and the GPX Shares unless the
                  sale of such securities has been so registered or such
                  registration is not required in the reasonable opinion of
                  counsel reasonably satisfactory to the Purchaser.
                  "THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN
                  ACQUIRED FOR INVESTMENT AND NOT WITH A VIEW TO, OR IN
                  CONNECTION WITH, THE SALE OR DISTRIBUTION THEREOF. NO SUCH
                  SALE OR DISPOSITION MAY BE EFFECTED WITHOUT AN EFFECTIVE
                  REGISTRATION STATEMENT RELATED THERETO OR AN OPINION OF
                  COUNSEL SATISFACTORY TO THE COMPANY THAT SUCH REGISTRATION IS
                  NOT REQUIRED UNDER THE SECURITIES ACT OF 1933."





         5. Additional Covenants.

          (a) At the  Closing,  Seller  and  Purchaser  agree to  enter  into an
agreement substantially in the form set forth as Exhibit -------- B. -

          (b) Except as required by law or stock  exchange  regulation,  neither
Purchaser nor Seller may issue any public  release  announcing or describing the
transaction  contemplated  by this  Agreement  without  the  other's  review and
approval of the release or announcement,  provided,  however,  in no event shall
such approval be unreasonably withheld, delayed or conditioned.

          (c) Seller  agrees  (and  agrees to cause its  affiliates)  during the
three-year period commencing on the Closing Date (as hereinafter defined) not to
engage or have any interest,  directly or indirectly,  in the nuclear simulation
or related training business (a "Competing Business").

          (d)  Notwithstanding  Section  5(c),  Seller  shall  have the right to
acquire a company (the "Acquired Company") with a Competing  Business,  provided
that the revenues of the  Competing  Business  constituted  for the prior fiscal
year, and constitute  (on an annualized  basis)at the time of such  acquisition,
less than the lesser of (i) 10% of the revenues of the Acquired Company and (ii)
$20,000,000. If Seller acquires or proposes to acquire such an Acquired Company,
the Purchaser shall have the one-time right and option to purchase the Competing
Business,  either  from  Seller  or in place  of  Seller,  as long as  Purchaser
provides  Seller  written  notice  thereof  within  thirty (30) days of Seller's
public  announcement of its intent to purchase the Acquired  Company.  If Seller
does not receive  notice from  Purchaser of its option to purchase the Competing
Business  within the 30-day notice  period,  then  Purchaser's  one-time  option
hereunder  expires and Seller may hold or dispose of the  Competing  Business in
its sole and absolute discretion.  Purchaser further agrees that in the event it
exercises  its one-time  option to purchase the  Competing  Business,  Purchaser
shall complete its purchase of the Competing  Business within sixty (60) days of
its election to  purchase.  Notwithstanding  the  foregoing,  in the  reasonable
option of Seller,  in the event the exercise of  Purchaser's  option to purchase
and/or the resulting completion of the sale of the Competing Business in any way
disrupts or delays  Seller's  purchase  and/or closing of the Acquired  Company,
upon written notice from Seller, Purchaser shall withdraw its option to purchase
the Competing  Business until after Seller publicly  announces its completion of
the  purchase of the Acquired  Company.  Seller shall then have 30 days from the
Seller's public  announcement of its completed  purchase of the Acquired Company
to exercise its option to purchase.

         (e) The acquisition by Purchaser of the Competing Business pursuant to
its option under Section 5(d) shall be on the same terms and conditions as
Seller's acquisition of the Acquired Company, provided, however, that the
purchase price of the Competing Business shall be equal to the product of (i)
the purchase price paid or to be paid by Seller for the Acquired Company
(including the Competing Business) and (ii) the percentage of the Acquired
Company's revenues for the prior fiscal year that was generated by the Competing
Business. Notwithstanding the foregoing, the purchase price shall also be
reasonably adjusted for balance sheet differences.



          (f)  Purchaser  and Seller agree to execute and deliver or cause to be
executed and delivered  such  additional  instruments  or documents as the other
party hereto may  reasonably  request for the purpose of carrying out the intent
of this Agreement.

          6. Conditions Precedent.

          (a) The  obligations  of Seller  hereunder  shall be subject to Seller
having the right to convert the 39,000 shares of Series A Convertible  Preferred
Stock of GSE owned by Seller into 2,511,915 shares of common stock of GSE.

          (b) The  obligations  of Purchaser  hereunder  shall be subject to its
receipt of the consent of its lenders to the  transaction  contemplated  hereby,
and the appointment by the Board of GSE of the additional  nominees of Purchaser
constituting half of the total number of directors of GSE then in office.

          (c) The  obligations  of  Seller  hereunder  shall be  subject  to the
receipt of the consent of its lenders to the transaction contemplated hereby.

          7. Closing.

          (a) The closing of the transactions (the "Closing") contemplated under
this Agreement  shall be held on the later to occur of (i)  satisfaction  of the
conditions  precedent as set forth in Section 6 herein and (ii) October 21, 2003
(the "Closing Date"),  at such time and place as the parties shall agree. (b) At
Closing, Seller shall deliver to Purchaser:

              (i)  stock  certificates  representing  the GSE  Shares,  properly
              endorsed for transfer to, or  accompanied by a duly executed stock
              power in favor of, Purchaser;

              (ii)  the  GSE  Note  accompanied  by  duly  executed   assignment
              documents,  if  applicable;  and  (iii)  an  executed  copy of the
              agreement substantially in the form set forth as Exhibit B.

              (c) At Closing,  Purchaser  shall deliver to Seller:  (i) the duly
              executed  GPX Note;  and (ii) an  executed  copy of the  agreement
              substantially in the form set forth as Exhibit B.

          (d) If the  Closing  shall not have  occurred by  November  15,  2003,
either  party may  terminate  this  Agreement  by notice to the other.  Upon any



termination  of this  Agreement  pursuant to this Section 7(d),  this  Agreement
shall  become  wholly void and of no further  force or effect and neither of the
parties  shall have any liability or obligation to the other arising out of this
Agreement  except  for any  liability  arising  from a  party's  breach  of this
Agreement prior to such termination.

                  8. Indemnification.

     (a) Seller  covenants and agrees to indemnify  and hold harmless  Purchaser
and its directors,  officers,  employees and agents from and against all losses,
damages,   costs  and  expenses  (including,   without  limitation,   reasonable
attorneys'  fees) arising out of or relating to any claims incurred or sustained
by Purchaser on account of any breach of any representation, warranty, covenant,
or agreement of Seller contained in this Agreement.

     (b) Purchaser  covenants  and agrees to indemnify and hold harmless  Seller
and its directors,  officers,  employees and agents from and against all losses,
damages,   costs  and  expenses  (including,   without  limitation,   reasonable
attorneys' fees) arising from or relating to any claims incurred or sustained by
Seller on account of any breach of any  representation,  warranty,  covenant  or
agreement of Purchaser contained in this Agreement.

         9. Survival. The representations, warranties, covenants and agreements
in this Agreement together with the indemnification provisions related thereto
shall survive the Closing until all obligations under the GPX Note have been
satisfied in full by repayment and/or conversion into GPX Stock, at which time
they shall terminate and no claim shall thereafter be brought in respect of
them; provided, however, that (a) such termination shall not affect any claim
for breach of any representation or warranty if written notice thereof, in
reasonable detail, has been given to the breaching party prior to such
termination date (in such case, the survival period for the representation and
warranty shall continue until the claim is fully resolved) and (b) the
representations and warranties contained in Sections 4(c) and 4(e) together with
the indemnification provisions related thereto shall survive the Closing without
limitation and shall not terminate.

     10. General Provisions.

     (a) This Agreement  shall be governed by the laws of the State of New York,
without giving effect to conflict of law provisions.  This Agreement  represents
the entire agreement between the parties with respect to the purchase of the GSE
Securities by Purchaser and may only be modified or amended in writing signed by
both parties.

     (b) Any  notice,  demand or request  required or  permitted  to be given by
either Seller or Purchaser  pursuant to the terms of this Agreement  shall be in
writing and shall be deemed given when  delivered  personally or via  nationally
recognized overnight carrier at the address of the party set forth below or such
other  address as either  party may  request  by  notifying  the other  party in
writing.



                  If to Purchaser, addressed to:

                           GP Strategies Corporation
                           777 Westchester Avenue
                           White Plains, NY 10604
                           Attention:  General Counsel

                  If to Seller, addressed to:

                           ManTech International Corporation
                           12015 Lee Jackson Highway
                           Fairfax, Virginia  22033-3300
                           Attention:  Office of General Counsel

     (c) The rights and  obligations of each party under this Agreement may only
be  assigned  with the prior  written  consent  of the  other and any  purported
transfer  otherwise  shall be null and  void.  Notwithstanding  anything  stated
herein to the contrary,  Purchaser agrees that all of Seller's right,  title and
interest in and to this Agreement has been, or will be collaterally  assigned to
its current and future lenders (currently Citizen's Bank of Pennsylvania, acting
in its capacity as the  administrative  agent for the lender  parties) which are
parties to that certain Business Loan and Security  Agreement dated December 17,
2001 (as the same has been and may be amended, modified, substituted or replaced
from time to time) and Purchaser  will continue to be bound by all the terms and
provisions  of this  Agreement  as it may relate to (or be enforced by) Seller's
lenders as successors and assigns hereunder.

     (d) Either  party's  failure to enforce any provision or provisions of this
Agreement shall not in any way be construed as a waiver of any such provision or
provisions,  nor prevent that party  thereafter  from  enforcing  each and every
other provision of this Agreement. The rights granted to both parties herein are
cumulative and the assertion of a remedy shall not constitute a waiver of either
party's  right to assert  all other  legal  remedies  available  to it under the
circumstances.

     (e) Except as  provided  in Section 8,  nothing  herein  contained  will be
deemed to create any third party  beneficiaries  or confer any benefit or rights
on or to any person not a party  hereto,  and no person not a party hereto shall
be entitled to enforce any provisions hereof or exercise any rights hereto.

     (f) Purchaser and Seller each  acknowledges that it has had the opportunity
to obtain the advice of  experienced  counsel of its own choosing in  connection
with the  negotiation  and  execution of this  Agreement and to confer with such
counsel with respect to all matters  contained  herein and that this  Agreement,
and any related  documents or agreements,  will not be construed against any one
party merely because that party may have caused it to be prepared.



     (g) This  Agreement may be executed by facsimile  signature and in multiple
counterparts,  each to be an  original  and both of which taken  together  shall
constitute one and the same document.

     (h) If any  restriction  contained  in  Section  5(c) shall be deemed to be
invalid,  illegal,  or  unenforceable  by reason  of the  extent,  duration,  or
geographical   scope  thereof,   or  otherwise,   then  the  court  making  such
determination shall have the right to reduce such extent, duration, geographical
scope,  or other  provisions  hereof,  and in its reduced form such  restriction
shall then be  enforceable  in the manner  contemplated  hereby.  If any clause,
provision  or section of this  Agreement  other than  Section 5(c) shall be held
illegal or invalid by any court,  the  illegality  or invalidity of such clause,
provision  or section  shall not affect the  remainder of this  Agreement  which
shall be construed and enforced as if such illegal or invalid clause,  provision
or  section  had not been  contained  in this  Agreement.  If any  agreement  or
obligation  contained in this  Agreement is held to be in violation of law, then
such  agreement or obligation  shall be deemed to be the agreement or obligation
of the respective party hereto only to the extent permitted by law.

     (i) The descriptive  headings of the several sections of this Agreement are
inserted for  convenience  only and shall not be deemed to affect the meaning or
construction of any of the provisions hereof.





          <<<<<<<<<<<<<<<<<<Signatures Follow on Next Page>>>>>>>>>>>>>





         IN WITNESS WHEREOF, the parties have duly executed this Agreement as of
the day and year first set forth above.



PURCHASER:                              SELLER:

GP Strategies Corporation               ManTech International Corporation




By:      /s/ Scott N. Greenberg        By:      /s/  John A. Moore, Jr.
Name:    Scott N. Greenberg                     Name: John A. Moore, Jr.
Title:   President and Chief                    Title: Executive Vice President
         Financial Officer


Witness/Attest                         Witness/Attest


/s/ Andrea D. Kantor
- ------------------------------------   -----------------------------------