Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  van Lingen Dennis
 2. Date of Event Requiring Statement (Month/Day/Year)
05/15/2006		 3. Issuer Name and Ticker or Trading Symbol
FORRESTER RESEARCH INC [FORR]
(Last)
(First)
(Middle)
FORRESTER RESEARCH, INC., 400 TECHNOLOGY SQUARE		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
President, EMEA
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

CAMBRIDGE, MA 02139		 6. Individual or Joint/Group Filing(Check Applicable Line)
_X_ Form filed by One Reporting Person
___ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares
Incentive Stock Option (right to buy)   (1) 03/30/2015 Common Stock 5,000 $ 14.06 D  
Incentive Stock Option (right to buy)   (2) 03/30/2013 Common Stock 5,000 $ 14.73 D  
Incentive Stock Option (right to buy)   (2) 03/15/2011 Common Stock 2,502 $ 25.16 D  
Non-Qualified Stock Option (right to buy)   (2) 03/15/2011 Common Stock 2,498 $ 25.16 D  
Non-Qualified Stock Option (right to buy)   (3) 09/30/2013 Common Stock 4,000 $ 13.94 D  
Non-Qualified Stock Option (right to buy)   (2) 03/30/2014 Common Stock 8,000 $ 18.42 D  
Incentive Stock Option (right to buy)   (4) 07/31/2010 Common Stock 4,896 $ 61.25 D  
Non-Qualified Stock Option (right to buy)   (4) 07/31/2010 Common Stock 104 $ 61.25 D  

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
van Lingen Dennis
FORRESTER RESEARCH, INC.
400 TECHNOLOGY SQUARE
CAMBRIDGE, MA 02139		       President, EMEA  

Signatures

Kimberly A. Maxwell, attorney in fact for Dennis van Lingen 05/17/2006
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) The options are subject to forfeiture in the event Forrester does not achieve earnings per share ("EPS") targets established by the Compensation and Nominating Committee of the Board of Directors for fiscal 2005. If the EPS target is met, the options vest in annual increments over either two or three years from the date of grant, depending on the level of EPS achieved.
(2) The Options become exercisable in four equal installments on the first, second, third, and fourth anniversaries of the grant date.
(3) The Options become exercisable on the first anniversary of the grant date.
(4) The Options become exercisable in three equal installments on the first, second and third anniversaries of the grant date.

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