SECURITIES AND EXCHANGE COMMISSION
Washington, D. C. 20549
SCHEDULE 13G
Under the Securities Exchange Act of 1934
(Amendment No. )
Corporate Office Properties
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(Name of Issuer)
COMMON STOCK
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(Title of Class of Securities)
22002T108
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(CUSIP Number)
December 31, 2005
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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).
CUSIP Number 22002T108 PAGE 1 OF 5 PAGES
1. Name of Reporting Person
Adelante Capital Management LLC
S.S. or I.R.S. Identification No. of Above Person
I.R.S. No. 943219135
2. Check the Appropriate Box if a Member of a Group*
(a) [ ]
(b) [ ]
3. SEC USE ONLY
4. Citizenship or Place of Organization: Delaware
5. Sole Voting Power
1,468,991
6. Shared Voting Power
27,600
7. Sole Dispositive Power
2,782,280
8. Shared Dispositive Power
0
9. Aggregate Amount Beneficially Owned by Each Reporting Person
2,782,280
10. Check Box if the Aggregate Amount in Row (9) Excludes Certain
Shares*
N/A
11. Percent of Class Represented by Amount in Row 9
7.03%
12. Type of Reporting Person
IA
CONTINUED ON NEXT PAGE
*SEE INSTRUCTIONS BEFORE FILLING OUT!
PAGE 2 OF 5 PAGES
ITEM 1. (a) Name of Issuer: Corporate Office Properties
(b) Address of Issuer's Principal Executive Offices
8815 Centre Park Drive, Suite 400; Columbia, MD 21045
ITEM 2. (a) Name of Person Filing
Adelante Capital Management LLC
(b) Address of Principal Business Office or, if none,
Residence
555 12th Street, Suite 2100, Oakland, CA 94607
(c) Citizenship: Delaware
(d) Title of Class of Securities: Common stock
(e) CUSIP Number: 22002T108
ITEM 3. If this statement is filed pursuant to Rule 13d-1(b), or 13d-2(b),
check whether the person filing is a:
(a) [ ] Broker or Dealer registered under Section 15 of the Act
(b) [ ] Bank as defined in section 3(a)(6) of the Act
(c) [ ] Insurance Company as defined in section 3(a)(19) of the Act
(d) [ ] Investment Company registered under section 8 of the
Investment Company Act of 1940
(e) [X] Investment Adviser registered under section 203 of
Investment Advisors Act of 1940
(f) [ ] Employee Benefit Plan, Pension Fund which is subject to the
provisions of the Employee Retirement Income Security Act
of 1974 or Endowment Fund; see Sec. 240.13d-1(b)(1)(ii)(F)
(g) [ ] Parent Holding Company, in accordance with Sec.
240.13d-1(b)(ii)(G) (Note: See Item 7)
(h) [ ] Group, in accordance with Sec. 240.13d-1(b)(1)(ii)(H)
PAGE 3 OF 5 PAGES
Item 4. Ownership
If the percent of class owned, as of December 31 of the year covered by the
statement, or as of the last day of any month described in Rule 13d-1 (b)
(2), if applicable, exceeds five percent, provide the following information
as of that date and identify those shares which there is a right to acquire.
(a) Amount Beneficially Owned
2,782,280
(b) Percent of Class
7.03%
(c) Number of shares as to which such person has:
(i) sole power to vote or to direct the vote
1,468,991
(ii) shared power to vote or to direct the voted
27,600
(iii) sole power to dispose or to direct the disposition of
2,782,280
(iv) shared power to dispose or to direct the disposition of
0
Item 5. Ownership of Five Percent or Less of a Class
If this statement is being filed to report the fact that as of the date
hereof the reporting person has ceased to be the beneficial owner of more
than five percent of the class of securities, check the following [ ].
Not Applicable
Item 6. Ownership of more than Five Percent on Behalf of Another Person.
If any other person is known to have the right to receive or the power to
direct the receipt of dividends from, or the proceeds from the sale of, such
securities, a statement to that effect should be included in response to this
item and, if such interest relates to more than five percent of the class,
such person should be identified. A listing of the shareholders of an
investment company registered under the Investment Company Act of 1940 or the
beneficiaries of employee benefit plan, pension fund or endowment fund is not
required.
All shares owned on behalf of our clients
PAGE 4 OF 5 PAGES
Item 7. Identification and Classification of the Subsidiary which Acquired
the Security Being Reported on by the Parent Holding Company.
If a parent holding company has filed this schedule, pursuant to Rule 13d-
1(b)(ii) (G), so indicated under Item 3 (g) and attach an exhibit stating the
identity and the Item 3 classification of the relevant subsidiary. If a
parent holding company has filed this schedule pursuant to Rule 13d-1 (c),
attach an exhibit stating the identification of the relevant subsidiary.
Not Applicable.
Item 8. Identification and Classification of Members of the Group
If a group has filed this schedule pursuant to Rule 13d-1(b) (ii) (H), so
Indicate under item 3 (h) and attach an exhibit stating the identity and Item
3 classification of each member of the group. If a group has filed this
schedule pursuant to Rule 13d-1 (c) attach an exhibit stating the identity of
each member of the group.
Not Applicable.
Item 9. Notice of Dissolution of Group
Notice of dissolution of a group may be furnished as an exhibit stating the
date of dissolution and that all further filings with respect to transactions
in the security reported on will be filed, if required, by members of the
group, in their individual capacity. See Item 5.
Not Applicable.
Item 10. Certification
The following certification shall be included if the statement is filed
Pursuant to Rule 13d-1(b):
By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were acquired in the ordinary course of business
and were not acquired for the purpose of and do not have the effect of
changing or influencing the control of the issuer of such securities and were
not acquired in connection with or as a participant in any transaction having
such purposes or effect.
PAGE 5 OF 5 PAGES
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 as of December 31, 2005.
ADELANTE CAPITAL MANAGEMENT LLC
By: /s/ Mark A. Hoopes
Name: Mark A. Hoopes
Title: Compliance Officer