ASGN Inc — Director's Dealing 2012

May 17, 2012

SEC Form 3 — Initial Statement of Beneficial Ownership

Issuer: ON ASSIGNMENT INC (ASGN)
CIK: 0000890564
Period of Report: 2012-05-15

Reporting Person: Callaghan Brian J. (Director, Member of 10% owner group)

Holdings (Non-Derivative)

Security	Shares	Ownership
Common Stock	3730230	Direct

Footnotes

F1: Par Value $.01 per share

F2: 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.