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 *
  Sheridan Edwin A.
 2. Date of Event Requiring Statement (Month/Day/Year)
05/15/2012		 3. Issuer Name and Ticker or Trading Symbol
ON ASSIGNMENT INC [ASGN]
(Last)
(First)
(Middle)
211 N. UNION STREET, SUITE 220		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) __X__ Other (specify below)
Member of 10% owner group
 5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

ALEXANDRIA, VA 22314		 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)
Common Stock (1) 3,730,230 (2)
D
 

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

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Sheridan Edwin A.
211 N. UNION STREET, SUITE 220
ALEXANDRIA, VA 22314		   X     Member of 10% owner group

Signatures

By: Power of Attorney, James L. Brill, CFO For: Edwin A. Sheridan 05/17/2012
**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) Par Value $.01 per share
(2) Of the aggregate number of shares reported, 291,874 shares are held in escrow in connection with the transactions contemplated by the Agreement of Merger, dated as of March 20, 2012, by and among On Assignment, Inc., a Delaware corporation, OA Acquisition Corp., a Virginia corporation and a wholly-owned subsidiary of On Assignment, Inc., Apex Systems, Inc., a Virginia corporation, and Jeffrey E. Veatch as representative of the shareholders of Apex Systems, Inc.

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