<PAGE>
                                                                   June 1, 1997
                                     
                                     
                                     
                                     
                                     
                            SUBLEASE AGREEMENT
                                     
This Sublease Agreement (the "Sublease"), is made as of the second
day of June, 1997 by and between LUCAS INDUSTRIES, INC., a Michigan
corporation ("Sublessor), and PSINET, INC., a New York corporation
("Sublessee").







                                 RECITALS
                                     

    A.   By Office Lease dated September 12, 1989, with attached
         Riders 1 and 2, as amended by that certain First
         Amendment To Lease dated December 20, 1989, and that
         certain Second Amendment To Lease dated July 31, 1990,
         and that certain Third Amendment To Lease dated August
         20, 1990, (collectively, the "Overlease"), 3B Limited
         Partnership, a Virginia limited partnership (Lessor),
         leased to Lucas Industries, Inc., a Michigan corporation,
         as lessee, the Demised Premises (defined below) located
         in the office building at 11180 Sunrise Valled Drive,
         Reston, Virginia (the "Building"), at the rent and upon
         and subject to the terms and conditions set forth in the
         Overlease.

    B.   CarrAmerica Realty Corporation (formerly known as Carr
         Realty Corporation is successor by purchase to 3B Limited
         Partnership under the Overlease.





                                    1
<PAGE>

                                                                   June 1, 1997


    C.   Sublessee desires to sublet from Sublessor all of the
Demised Permises and Sublessor desires to sublet the Demised
Premises at the rent and upon the terms and conditions set forth
herein.



    NOW, THEREFORE, in consideration of the premises, the mutual
promises set forth herein, and for other good and valuable
consideration, the receipt and sufficiency of which is hereby
acknowledged, the parties hereto, for themselves, their successors
and assigns, mutually covenant and agree as follows:







    1.      Demised Premises

    (a)     Demised Premises.  Sublessor does hereby sublease to
    Sublessee, the Sublessee does hereby sublease from Sublessor,
    for the Term (defined hereinafter) and upon the conditions
    hereinafter provided, approximately 13,518 rentable square
    feet (the "Demised Premises"), which has been determined and
    certified in accordance with the 1989 Washington, D.C.
    Association fo Realtors Standard Method of Measurement (the
    "Standard"), comprising a portion of the Third (3rd) Floor of
    the Building.  The Demised Premises is approximately 13,518
    square feet.  The floor plan is attached hereto and made a
    part hereof as Exibit A.


    (2)     Term.   The term of the Sublease (the "Term") shall
commence on the later of July 11, 1997 or the day Sublessor's
furniture is removed from the Demised Premises 

                                    2
<PAGE>

                                                                   June 1, 1997


and the Demised Premises is delivered to Sublessee in broom clean
condition (the "Sublease Commencement Date"), and shall end on (i)
July 21, 2000, or (ii) the date upon which the Term may be
terminated pursuant to any of theconditions or limitations or other
provisions of this Sulease or by operation of law.  Sublessee's
contractors shall have access to the premises for planning and
network/phone installation purposes, coordinated with a Sublessor
representative, commencing July 1, 1997.  If the premises are not
ready for Sublessee's possession on or before August 1, 1997, as a
result of a delay caused by the Sublessor or his agent, Sublessee
may cancel this Sublease.







    3.  Base Rent.   The annual base rent, which Sublessee hereby
agrees to pay to Sublessor and Sublessor hereby agrees to accept
shall be a sum equal to the product of twenty-Two Dollars ($22.00)
multiplied by the number of rentable square feet (13,518), as
certified pursuant to the Standard, in the Demised Premises (the
"Base Rent").  The Base Rent shall be inclusive of Real Estate
Taxes and all other Operating Costs (as such terms are defined in
the Overlease).  The obligation of Sublessee to pay Base Rent shall
begin on the Sublease Commencement Date.  The annual Base Rent
payable during each Sublease Year, as hereinafter defined, shall be
divided into twelve (12) equal monthly installments and such
monthly installments shall be due and payable in advance, on the
first day of each month during each Sublease Year.  For the
purposes of this Sublease, the term "Sublease Year" shall mean a
period of twelve (12) consecutive months, commencing on the
Sublease Commencement Date, and each successive twelve (12)  


                                    3
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                                                                   June 1, 1997


Month period thereafter, except that, if the Sublease Commencement
Date is a day other than the first day of a month, then the first
Sublease Year shall commence on the Sublease Commencement Date and
shall continue for the balance of the month in which the Sublease
Commencement Date occurs and for a period of twenve (12)
consecutive calendar months after the last day of such month.  If
the Sublease Commencement Date is a day other than the first day of
a month, then, in the first Sublease Year, said twelve (12)
installments shall be payable beginning on the first day of the
calendar month immediately following the month in which the
Sublease Commencement Date occurs and, in additions, on the
Sublease Commencement Date, a payment of Base Rent shall be payable
in an amount equal to the product of the annual Base Rent then in
effect and a fraction, the numerator of which is the number of days
of the Sublease Term in the month in which the Sublease
Commencement Date occurs, and the denominator of which is 365.  The
monthly Base Rent, Additional Rent (as defined herein), and any
other charges herein reserved or payable shall be paid to Sublessor
by wire transfer to the account of: Lucas Industries Inc, Account
Number 3900-0965 Cititbank NY, ABA #021-000-089 with written
confirmation of such transfer to the Sublessor at its offices at
12025 Tech Center Drive, Livonia, Michigan 48150, Attention: Mr.
Ian McaNeill or at such other place as Sublessor may designate in
writing, in lawful money of the United States of America, without
demand therefor and without any deduction, setoff or abatement
whatever, except as expressly provided in this Sublease.  In the
event that Sublessee does not remit any payment due under this
Sublease to Sublessor within seven (7) calendar 

                                    4
<PAGE>


                                                                   June 1, 1997


days of when it is due, such amount shall be subject to a late fee
of 5% of the amount, and bear interest at 2% over the Wall Street
Journal Prime Rate until paid.







    4.   Annual Base Rent Escalation.  The annual Base Rent shall
be increased, effective as of the first day of each succeeding
Sublease Year after the first Sublease Year, by an amount equal to
Three Percent (3%) of the annual Base Rent in effect during the
Sublease Year preceding the applicable adjustment.  The attached
Exhibit B, incorporated herein by this reference, sets forth the
annual Base Rent during the Term.






    5.   Additional Rent.  Beginning on the first day of the
second (2nd) Sublease Year, and on the first day of each Sublease
Year thereafter, Sublessee agrees to pay to Sublessor, as
additional rent under this Sublease, Sublessor's Pro-Rata Share
(defined below) of increases in the Real Estate Taxes and Operating
Costs (as such terms are defined in the Overlease), over the Real
Estate Taxes and Operating Costs for calendar year 1997, grossed-up
to reflect that the Building was a fully leased and fully assessed
building for Real Estate Taxes and Operating Expenses throughout
calendar 1997 and each of the Sublease Years being compared (the
"Additional rent").  Any Additional Rent which may be payable to
Sublessor in any Sublease Year shall be apportioned such that
Sublessee shall be obligated to pay to Sublessor a proporationate
share of such Additional 

                                    5
<PAGE>

                                                                   June 1, 1997

Rent which is attributable to the number of days in the Sublease
Year.  For the purpose of this Sublease, Sublessor and Sublessee
agree that Sublessor's Pro-Rata Share is equal to a fraction, the
numerator of which is the number of Gross Rentable Area of the
Demised Premises, and the denominator of which is the number of
Gross Rentable Office Are of the Building.  Sublessee shall also
pay to Sublessor, or Lessor as Additional Rent, all charges for any
additional services provided by Sublessor or Lessor to Sublessee
which Sublesee requests and not provided for or allocated in this
Sublease or int eh Overlease.







    6.  Building Services, Parking, Security.


    (a)     Services.   Building cleaning services, electrical and
    lighting service, water and sewer service, and heating,
    ventilation and air-conditioning will be provided to Sublessee
    in accordance with Lessor's obligations to Sublessor under
    Paragraph 16 of the Overlease.  Sublessee shall be allowed
    access to the Building and the Demised Premises twenty-four
    (24) hours per day, seven (7) days per week.  At least one (1)
    elevator shall be in use and available for Sublessee's use at
    all times.  Sublessee shall observe Lessor's requirements
    related to moving construction materials, furnishings and
    equipment into or out of the Demised Premises and the
    Building.  Sublessor shall use reasonable efforts to assist
    Sublessee in having Lessor provide Sublessee with a listing on
    the monument sugn in front and in the Building directory at
    Sublessee's expense.

                                    6
<PAGE>

                                                                   June 1, 1997


    (b)     Parking.  Sublessor shall allocate to and allow
    Sublessee to use, at no additional cost to Sublessee, 43
    Sublessor's allocation of unreserved parking spaces in the
    Building's covered parking structure and/or surface parking
    lot.  Sublessor shall allocate to and allow Sublessee
    exclusive use of the six (6) reserved, covered, and marked
    parking spaces allocated to the Sublessor in the parking
    structure shown on Exhibit C attached hereto as part of the
    parking allocation hereunder at no additional cost to
    Sublessee.  Sublessor shall use reasonable efforts to assist
    Sublessee to obtain from sublessor six (6) reserved parking
    signs at Sublessee's expense, if any.  The Building parking
    structure and lot will be accessible to Sublessee twenty-foru
    (24) hours per day, seven (7) days per week.








    (c)     Security.  Sublessor will cause Lessor to provide an
    electronic card or key access system for Sublessee's use,
    monitored at all Building entrances, and elevators in
    accordance with Paragraph 16 of the Overlease.  The Sublessor
    will provide to Sublessee any such access cards and keys in
    their possession at the Sublease commencement date.  All
    subsequent cards and keys shall be requested from the Lessor
    or the Lessor's designee and provided at the Sublessee's
    expense.  Sublessee shall be responsible for maintaining an
    accurate listing of all electronic cards or keys provided to
    employees.  All costs associated with the granting and
    maintaining of the electronic card or key access system shall
    be the responsibility of the Sublessee.

                                    7
<PAGE>

                                                                   June 1, 1997


    7.  Deposit.  Upon execution of this Sublease, Sublessee shall
supply Sublessor with a letter of credit in a form and from an
institution reasonably acceptable to Sublessor in the amount equal
to six (6) months of base rental payments to be held for the
duration of the Sublease Term.  Provided, however, that if
Sublessee is not in default at the end of the eighteenth (18th)
month and the Sublessor's net worth at the eighteenth (18) month is
equal to or better than its net worth at the Sublease execution
date, said letter of credit shall be reduced by one-half.  The
letter of credit provided herein shall be considered as partial
security for the payment and performance by, Sublessee of all of
Sublessee's obligations, covenants, conditions and agreement under
this Sublease.  Whenever Sublessee shall be in default for thirty
(30) days or more, Sublessor shall be entitled to the proceeds from
the letter of credit and to demand a new letter of credit be put
into place.



For purposes of this Sublease, net worth shall mean all amounts in
respect of the Sublessee's capital stock, plus the amounts of
additional paid in capital, retained earnings and other items
designated as part of the Sublessee's stockholders' equity all of
which would appear as such on a consolidated balance sheet of the
Sublessee, less the amounts of goodwill or other intangible assets
of the Sublessor, all as of such date prepared in accordance with
UN Generally Accepted Accounting Principles (GAAP).



The Sublessee shall furnish to the Sublessor, the following
financial statements, reports,

                                    8
<PAGE>

                                                                   June 1, 1997

And information as of the sublease execution date and at the
eighteenth (18) month:



    (a)     promptly when available and in any event within 30 days
    after the execution date and the end of the eighteenth (18)
    month, an unaudited consolidated balance sheet of the
    Sublessee and its consolidated subsidiaries certified as to
    fairness and accuracy of presentation and compliance and
    consistency with GAAP by the chief accounting or financial
    officer of the Sublessee.




    (b)     Simultaneously with the delivery of the financial
            statements referred to in a) above, a certificate of
            the chief accounting or financial officer of the
            Sublessee setting forth in reasonable detail whether
            the Sublessee was in compliance with the Net Worth
            requirement on the date of such financial statements
            and certifying that no default exists on the date of
            delivery of such certificate.



    8.  Use.   Sublessee will use and occupy the Demised Premises
solely for general office purposes and ancillary uses and in
accordance with the uses permitted under the Zoning Ordinance of
Fairfax County, Virginia.  Without the prior written consent of
Lessor and Sublessor, the Demised Premises will not be used for any
other purposes.  Sublessee hereby agrees to use the Demised
Premises in accordance with the Rules and Regulations of the
Overlease appended hereto as Exhibit D and incorporated by this
reference.



    9.  Subtenant Work and Alterations.

                                    9
<PAGE>

                                                                   June 1, 1997


    (a)     Cost of Improvements.   Sublessee shall accept
    possession of the Demised Premises as their "as is" condition
    as of the date of this Sublease.  Sublessee shall pay for the
    cost of planning, design, demolition and construction of
    improvements to the Demised Premises, to include all
    architectural and engineering services associated therewith
    (the "Subtenant Work"), whether performed by Lessor's or
    Sublessor's independent contractors.




    (b)     Design of Subtenant Work.  Following Sublessee's
    delivery of plans for the Subtenant Work (the "Subtenant Work
    Plan"), Sublessee shall provide a list of proposed contractors
    selected by Sublessee to perform the Subtenant Work to
    Sublessor and Lessor for approval, Sublessor shall use its
    reasonable efforts to obtain written consent from lessor to
    perform the Subtenant Work.  Sublessee shall pay any fees or
    reasonable out of pocket costs incurred in obtaining the
    consent from Lessor as contained in the Overlease.   The
    consent from Lessor will be based upon the Subtenant Work
    Plan's conformance to the requirements of the Zoning Ordinance
    of Fairfax County, Virginia, the contractors being properly
    licensed and experienced, and upon the conditions contained in
    the Overlease.  The consent of Lessor, once obtained, shall be
    deemed to include the consent of Sublessor.



    (c)     Construction of Subtenant Work.  Sublessee shall cause
    the Subtenant Work to be constructed in accordance with the
    Subtenant Work Plan and the Overlease, and in accordance with
    all applicable building codes of the Town of Reston, County of
    Fairfax, State of Virginia, and any applicable Federal 

                                    10
<PAGE>

                                                                   June 1, 1997


code including, but not limited to, the American Disabilities Act.





    (d)  Alterations.  Except as otherwise expressly provided in
    the Subtenant Work Plan, Sublessee shall not make any
    alteration, improvement, or installation other than
    corrective, cosmetic or decorative improvements hereinafter
    called ("Alterations") in or to the Demised Premises, without
    in each instance obtaining the prior written consent of
    Sublessor and Lessor (which consent of Sublessor shall not be
    unreasonably withheld, conditioned or delayed).  With
    reasonable notice to Sublessee, Lessor and Sublessor shall at
    all times upon reasonable notice during normal business hours
    with a Sublessee escort have the right to inspect the work
    performed by any contractor selected by Sublessee to perform
    the Subtenant Work and any Alterations.




    10.  Restoration.  Upon the expiration of the Term of this
Sublease, Sublessee shall surrender the Demised Premises in good
condition, subject only to reasonable wear and tear.




    10.  Enforcement of Overlease.  Except as otherwise expressly
provided herein, all of the terms, provisions, covenants and
conditions of this Sublease are subject to the Overlease (Exhibit
E).  In the event of a conflict between the Terms of this Sublease
agreement and the Overlease, the Terms of the Overlease shall
apply.  Sublessor and Sublessee shall each observe and perform all
of the terms, covenants and conditions hereunder.  Sublessor shall
observe and perform all applicable terms, covenants and

                                    11
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                                                                   June 1, 1997


Conditions as tenant under the Overlease with respect to the
Demised Premises; and Sublessee shall observe and perform all
applicable terms, covenant and conditions of the Overlease with
respect to the Demised Premises to which Sublessee at the sole
discretion of Sublessor may be subrogated in performing its
obligations under this Sublease.  Sublessee shall obtain and
maintain all insurance types and coverages as specified in the
Overlease to be obtained and maintained by Sublessor as "Tenant" in
amounts not less than those specified in the Overlease.  All
policies of Sublessee shall name Lessor and its Agent as additional
insureds thereon in accordance with the Overlease, and Sublessee's
insurance shall be primary over Lessor's, Agent's and Sublessor's. 
Except for riders 1 and 2 to the Overlease and as otherwise set out
in this Sublease, Sublessor agrees to subrogate Sublessee to the
rights and privileges of Sublessor under the Overlease, and agrees
to furnish for Sublessee the following services, including, without
limitation, the furnishing of electrical, lighting, heating,
Building standard ventilation and air-condition, water and sewer,
elevator service, cleaning, window washing, and rubbish removal
services, which include all services of which Lessor is obligated
to furnish to Sublessor pursuant to the Overlease.  Sublessor shall
use its best efforts to obtain and enforce the full performance by
Lessor pursuant to the terms of the Overlease.




    12.  Covenants and Warranties.


            (a)    Sublessor's Covenants.  Sublessor covenants,
warrant and agrees not 

                                    12
<PAGE>


                                                                   June 1, 1997



to do or omit to do anything which would constitute a default under
the Overlease, including without limitation anything which
Sublessor is obligated to do under the terms of this Sublease.



    (b)     Sublessee's Covenants.  Sublessee covenants and agrees
not to do or omit to do anything which would constitute a default
under the Overlease, including without limitation anything which
Sublessee is obligated to do under the terms of this Sublease.






    (c)     Warranty of No Default.  Sublessor warrants and
represents to Sublessee that the Overlease has not been amended or
modified except as expressly set forth in the recitals above, that
there is no cross-default or other contractual relationship between
the Overlease and Sublessor's lease covering the Fourth Floor at
the Building, that Sublessor is the tenant by operation of law
under the Overlease and has full capacity to enter into and perform
under this Sublease, that this Sublease will be binding and fully
enforceable against Sublessor, that Sublessor is not now, and as of
the Sublease Commencement Date will not be, in default or breach of
any term, condition or provision of the Overlease, and that
Sublessor has no knowledge of any claim by Lessor that Sublessor is
in default or breach of the Overlease.



    13.  Brokers.  Sublessor and Sublessee hereby represent and
warrant to the other that neither of them has employed or dealt
with any broker in connection with this Sublease for the Demised
Premises other than the firms of Grubb & Ellis of Metropolitan
Washington, D.C. and The Charles E. Smith Companies (representing
Sublessee), and

                                    13
<PAGE>

                                                                   June 1, 1997



Each hereby agrees to indemnify and hold harmless the other against
any claim by any other broker, agent or finder with whom the
indemnitor has dealt.  Sublessor shall be responsible for the
payment of the brokers' commissions to Grubb & Ellis, pursuant to a
separate agreement.





    14.  Indemnification.  Sublessor and Sublessee each shall and
hereby does indemnify and hold the other and Lessor harmless from
and against any and all actions, claims, demands, damages,
liabilities and expenses (including, without limitation, reasonable
attorneys' fees) asserted against, imposed upon or incurred by the
other or Lessor by reason of (a) any violation caused, suffered or
permitted by the indemnitor, its agents, servants, employees or
invitees, of any of the terms, covenants or conditions of the
Sublease or the Overlease and (b) any damage or injury to persons
or property occurring upon or in connection with the Building,
including without limitation, the Demised Premises, except as a
result of the acts or omissions of the indemnitor, or its
respective agents, employees or invitees.



    15.  Signage.   Sublessee shall have the right, at its sole
expense, to install signage on the west side of the Building
viewable from the Dulles Access road and Virginia route 267,
replacing the existing Lucas Sign, subject only to written consent
by Lessor and to any governmental restrictions.  Sublessor shall
use reasonable efforts to assist Sublessee to obtain Lessor's
written consent to such signage.  Sublessee shall be responsible
for the 

                                    14
<PAGE>

                                                                   June 1, 1997


cost of  installing its sign and for the cost of removal of the
Sublessor's sign.






    16.  Quiet Enjoyment.  Sublessor covenants that it has the
right to make this Sublease for the Term and upon all of the terms
and provisions hereof, and that if Sublessee pays the Base Rent and
Additional Rent and performs all of the covenants, terms and
conditions of this Sublease to be performed by Sublessee, then
Sublessee shall, during the Term, freely, peaceably and quietly
occupy and enjoy the full possession of the Demised Premises and
all rights under this Sublease granted to Sublessee, without
molestation or hindrance by Sublessor, Lessor, or any party
claiming through or under either Sublessor or Lessor.




    17.  Entire Agreement.  This Sublease contains all of the covenants, 
agreement, terms, provisions, conditions, warranties and understandings 
between the parties hereto relating to the subleasing of the Demised 
Premises.  All understandings and agreement, if any, between the parties are 
merged in this Sublease, which alone fully and completely expresses the 
agreement of the parties.  The failure of Sublessor or Sublessee to insist in 
any instance upon the strict observance or performance of any covenant, 
agreement, terms, provision or condition of this Sublease or to exercise any 
election herein contained shall not be construed as a waiver or 
relinquishment for the future of such covenant, agreement, term, provision, 
condition or election, but the same shall continue and remain in full force 
and effect.  No waiver or modification of any covenant, agreement, term, 
provision or condition of this Sublease shall be deemed to have been made 
unless 

                                    15
<PAGE>

                                                                   June 1, 1997


expressed in writing and signed by Sublessor and Sublessee.  No
surrender of possession of the Demised Premises or of any part
thereof or of any remainder of the Term of this Sublease shall
release Sublessor or Sublessee from any of its obligations
hereunder unless accepted by Sublessor and Sublessee in writing.





    18.  Successors and Assigns.  The obligations of this Sublease
shall bind and benefit the successors and permitted assigns of the
parties with the same effect as if mentioned in each instance where
a party hereto is named.  Sublessor has the right to assign this
agreement.




    19.  Notices.  Any and all communications delivered hereunder
shall be sent by first-class mail: if to Sublessor, at its offices
at 672 Delaware Avenue, Buffalo, New York 14209, Attention: Mr.
James Zigel or at such other place as Sublessor may designate in
writing; and if to Sublessee, at its offices at 11180 Sunrise
Valley Drive, Suite 300, Reston, Virginia, 20171, Attention:
General Counsel or to such other addresses as either of the above
shall notify the other in writing.



    20.  Binding Effect.  The terms and provisions of this
Sublease will inure to the benefit of, and will be binding upon,
the successors, assigns, personal representatives, heirs, devises
and legatees of the Sublessor and Sublessee.

                                    16
<PAGE>

                                                                   June 1, 1997


    21.  Severability.  If any term, provision, covenant or
condition of this Sublease is held by a court of competent
jurisdiction to be invalid, void or unenforceable, such term,
provision, covenant or condition shall be interpreted so as to be
enforceable to the fullest extent permitted by law, and the
remaining terms, provisions, covenants and conditions contained
herein shall not be affected thereby.





    22.  Headings.  The headings of the sections and subsections
used in this Sublease are inserted for the convenience of reference
only and are not intended to affect the meaning or interpretation
of this Sublease.





    23.  Governing Law.  This Sublease shall be governed by and
construed in accordance with the laws of the Commonwealth of
Virginia.







    24.  Lessor's Consent.  This Sublease shall be effective upon
the date Sublessee receives written consent to this Sublease by
Lessor.  It is hereby acknowledged by Sublessor and Sublessee that
Lessor's consent to this Sublease shall not make Lessor or its
Agent, Carr Real Estate Services Partnership (or Agent's
subcontractor, Carr Real Estate Services, Inc.) a party to this
Sublease, shall not create any contractual liability, privity or
duty on the part of Lessor or its Agent to the Sublessee, and shall
not in any manner increase, decrease, modify or otherwise affect
the rights and obligations of Lessor and Sublessor, as "Tenant"
under the Overlease, in respect to the Demised Property.

                                    17
<PAGE>

                                                                   June 1, 1997


    25.  Payment of Fees.  In the event either Sublessor or
Sublessee shall commence an action against the other (including
collections under bankruptcy) in respect to this Sublease, the
losing party shall pay the prevailing party all of its reasonable
costs and expenses in connection with such action, including but
not limited to reasonable attorney fees.




    IN WITNESS WHEREOF, Sublessor and Sublessee have duly executed
this Sublease under seal as of the day and year first above
written.







                   SUBLESSOR:     
                   LUCAS INDUSTRIES INC., a Michigan corporation



                   By:   /s/James M. Zigel
                     ---------------------

                   Name: James M. Zigel
                         -----------------
                   Title:  President   
                           ---------------

                                    18
<PAGE>

                                                                   June 1, 1997




                             SUBLESSEE:

                             PSINET, INC. a New York corporation

                             By: /s/Harold S. Wills
                                -------------------

                             Name: Harold S. Wills
                                   ---------------

                             Title: EVP & COO
                                    ---------


This Sublease is consented to by Lessor upon the terms and
conditions acknowledged by Sublessor and Sublessee in the Paragraph
of this Sublease entitled "Lessor's Consent" and in accordance with
the terms and conditions of the Overlease.  Lessor's consent shall
be required for an assignment of this Sublease or any further
subleasing of the Demised Premises or any portion thereof.


                   LESSOR:

                   CARRAMERICA REALTY CORPORATION, a Maryland
                   corporation (formerly known as Carr Realty
                   Corporation, as successor in interest to 3B
                   Limited Partnership as Landlord under the
                   Overlease)


By:  /s/Paul R. Adkins
    -----------------

Name: Paul R. Adkins
     --------------

Title: VP/Marketing Officer
      --------------------

                                    19
<PAGE>

Exhibit 10.2  The following Exhibits and Schedules have been
              omitted, which the Company agrees to furnish
              supplementally to the Commission upon request:


    Exhibit A: Map of Demised Premises
    Exhibit B: Base Rent Schedule
    Exhibit C: Parking Structure
    Exhibit D: Rules and Regulations
    Exhibit E: Description of Signs
    Exhibit F: Schedule of Taxes and Operating Costs
            Rider 1  Options to Renew
            Rider 2  Rent Abatement: First Amendment to Lease
            Exhibit A: Third Floor Plan
            Exhibit B: Base Rent Schedule