ASGN Inc — Director's Dealing 2013

May 9, 2013

SEC Form 4 — Statement of Changes in Beneficial Ownership

Issuer: ON ASSIGNMENT INC (ASGN)
CIK: 0000890564
Period of Report: 2013-05-07

Reporting Person: Gibson Christina (V.P., Finance and Controller)

Non-Derivative Transactions

Date	Security	Code	Shares	Price	A/D	Holdings After	Ownership
2013-05-07	Common Stock	S	989	$25	Disposed	13682	Direct
2013-05-07	Common Stock	M	250	$8.26	Acquired	13932	Direct
2013-05-07	Common Stock	S	250	$25	Disposed	13682	Direct
2013-05-07	Common Stock	M	500	$10.46	Acquired	14182	Direct
2013-05-07	Common Stock	S	500	$25	Disposed	13682	Direct
2013-05-07	Common Stock	S	960	$25	Disposed	12722	Direct
2013-05-07	Common Stock	S	301	$25	Disposed	12421	Direct

Derivative Transactions

Date	Security	Exercise Price	Code	Shares	A/D	Expiration	Underlying	Ownership
2013-05-07	Non-Qualified Stock Option (right to buy)	$8.26	M	250	Disposed	2021-01-19	Common Stock (250)	Direct
2013-05-07	Non-Qualified Stock Option (right to buy)	$10.46	M	500	Disposed	2021-12-07	Common Stock (500)	Direct

Footnotes

F1: One-fourth of the total number of options vest twelve months following the grant date and one forty-eighth of such amount vests thereafter on each monthly anniversary of the grant date.

F2: Grant Vests over a four-year period: 25% on one-year anniversary and equal monthly installments thereafter .