FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN 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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1. Name and Address of Reporting Person * Hanson Theodore S.   2. Issuer Name and Ticker or Trading Symbol ON ASSIGNMENT INC [ASGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President, ASGN (Last) (First) (Middle) ON ASSIGNMENT, INC., 26745 MALIBU HILLS ROAD 3. Date of Earliest Transaction (Month/Day/Year) 12/31/2017 (Street) CALABASAS, CA 91301 4. If Amendment, Date Original Filed(Month/Day/Year) 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 Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 12/31/2017   A   5,827 (1) A $ 0 238,313 D   Common Stock 12/31/2017   F   2,779 (2) D $ 64.27 235,534 D   Common Stock 12/31/2017   A   1,127 (1) A $ 0 236,661 D   Common Stock 12/31/2017   F   537 (2) D $ 64.27 236,124 D   Common Stock 12/31/2017   A   2,337 (1) A $ 0 238,461 D   Common Stock 12/31/2017   F   1,114 (2) D $ 64.27 237,347 D   Common Stock 12/31/2017   A   3,885 (1) A $ 0 241,232 D   Common Stock 12/31/2017   F   1,853 (2) D $ 64.27 239,379 D   Common Stock 12/31/2017   A   11,653 (3) A $ 0 251,032 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
Hanson Theodore S. ON ASSIGNMENT, INC. 26745 MALIBU HILLS ROAD CALABASAS, CA 91301			President, ASGN

Signatures

By: /s/ Jennifer Painter, CLO For: Theodore S. Hanson		01/03/2018
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(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 acquired shares vested upon certification of a performance target on December 31, 2017 for a performance award previously granted to the executive officer.
(2)	Executive Officer elected to satisfy his tax withholding obligations upon vesting by having the issuer withhold a number of vested shares equal to that of the officer's tax liability.
(3)	On December 31, 2017, performance targets were achieved for an RSU grant that was previously made to the executive officer. 50% of these RSUs will vest on January 3, 2019 and the remaining RSUs will vest on January 3, 2020, subject to the executive officer's continued service to the Company.

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