SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                   Under the Securities Exchange Act of 1934
                             (Amendment No._____)*

                       Corporate Office Properties Trust
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                                (Name of Issuer)

                    Common Shares, $.01 par value per share
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                         (Title of Class of Securities)

                                   22002T108
                        ------------------------------
                                 (CUSIP Number)

                               December 31, 2002
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            (Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

     [X] Rule 13d-1(b)
     [_] Rule 13d-1(c)
     [_] Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.


The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



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CUSIP No. 22002T108                 13G                       Page 2 of 6 Pages
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 1.   NAME OF REPORTING PERSON
      I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)

                 Security Capital Research & Management Incorporated
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 2.   CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*
                                                                (a) [_]
                                                                (b) [_]
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 3.   SEC USE ONLY

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 4.   CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
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                     5.   SOLE VOTING POWER

                              -0- Common Shares
  NUMBER OF        -------------------------------------------------------------
    SHARES           6.   SHARED VOTING POWER
 BENEFICIALLY
   OWNED BY                   1,791,988 Common Shares
     EACH          -------------------------------------------------------------
  REPORTING          7.   SOLE DISPOSITIVE POWER
    PERSON
     WITH                     -0- Common Shares
                   -------------------------------------------------------------
                     8.   SHARED DISPOSITIVE POWER

                              1,791,988 Common Shares
--------------------------------------------------------------------------------
 9.   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

            1,791,988 Common Shares
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10.   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES*

                                                                    [_]
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11.   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

                   7.54% of the Common Shares
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12.   TYPE OF REPORTING PERSON*

                   IA
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                     *SEE INSTRUCTIONS BEFORE FILLING OUT!




Item 1(a). Name of Issuer:

           Corporate Office Properties Trust

      (b). Address of Issuer's Principal Executive Offices:

           8815 Centre Park Drive, Suite 400, Columbia, Maryland 21045

Item 2(a). Name of Person Filing:

           Security Capital Research & Management Incorporated, a corporation
           organized and existing under the laws of Delaware ("SCR&M").

      (b). Address of Principal Business Office or, if None, Residence:

           11 South LaSalle Street, 2/nd/ Floor, Chicago, Illinois 60603

      (c). Citizenship:

           Delaware

      (d). Title of Class of Securities:

           Common Shares, $.01 par value per share

      (e). CUSIP Number:

           22002T108

Item 3.  If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b) or
         (c), check whether the person filing is a:

           (a) [_] Broker or dealer registered under Section 15 of the Exchange
                   Act;
           (b) [_] Bank as defined in Section 3(a)(6) of the Exchange Act;
           (c) [_] Insurance company as defined in Section 3(a)(19) of the
                   Exchange Act;
           (d) [_] Investment company registered under Section 8 of the
                   Investment Company Act;
           (e) [X] An investment adviser in accordance with Rule
                   13d-1(b)(1)(ii)(E);
           (f) [_] An employee benefit plan or endowment fund in accordance
                   with Rule 13d-1(b)(1)(ii)(F);
           (g) [_] A parent holding company or control person in accordance with
                   Rule 13d-1(b)(1)(ii)(G);
           (h) [_] A savings association as defined in Section 3(b) of the
                   Federal Deposit Insurance Act;
           (i) [_] A church plan that is excluded from the definition of an
                   investment company under Section 3(c)(14) of the Investment
                   Company Act;
           (j) [_] Group, in accordance with Rule 13d-1(b)(1)(ii)(J).



Item 4.  Ownership.

  (a).   Amount Beneficially Owned:

               SCR&M beneficially owns 1,791,988 Common Shares.

  (b).   Percent of Class:

               7.54% of the Common Shares determined in accordance with the
               provisions of Rule 13d-1 promulgated under the Act.

  (c).   Number of shares as to which such person has:

               (i).   Sole power to vote or to direct the vote:

                      None.

               (ii).  Shared power to vote or to direct the vote:

                      SCR&M has shared power to vote or direct the vote of
                      1,791,988 Common Shares.

               (iii). Sole power to dispose or to direct the disposition of:

                      None.

               (iv).  Shared power to dispose or to direct the disposition of:

                      SCR&M has shared power to dispose or to direct the
                      disposition of 1,791,988 Common Shares.

Item 5.  Ownership of Five Percent or Less of a Class.

               Not applicable.

Item 6.  Ownership of More than Five Percent on Behalf of Another Person.

               Various persons have the right to receive or the power to
               direct the receipt of dividends from, or the proceeds from the
               sale of, the Common Shares. No one person's interest in the
               Common Shares is more than five percent of the total
               outstanding Common Shares.

Item 7.  Identification and Classification of the Subsidiary Which Acquired the
         Security Being Reported on By the Parent Holding Company.

               Not applicable.



Item 8.  Identification and Classification of Members of the Group.

               Not applicable.

Item 9.  Notice of Dissolution of a Group.

               Not applicable.

Item 10. Certification.

         By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were acquired and are held in the
ordinary course of business and were not acquired and are not held for the
purpose of or with the effect of changing or influencing the control/ of the
issuer of the securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose or effect.



                                    SIGNATURE

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete and
correct.

Date: February 13, 2003


                                         SECURITY CAPITAL RESEARCH & MANAGEMENT
                                         INCORPORATED


                                         By: /s/ David T. Novick
                                            -----------------------------------
                                         Name:   David T. Novick
                                         Title:  General Counsel