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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(Print or Type Responses)

1. Name and Address of Reporting Person * DAMERIS PETER T   2. Issuer Name and Ticker or Trading Symbol ON ASSIGNMENT INC [ASGN] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Chief Executive Officer (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   17,929 (1) A $ 0 82,929 D   Common Stock 12/31/2017   F   9,851 (2) D $ 64.27 73,078 D   Common Stock 12/31/2017   A   77,319 (3) A $ 0 150,397 D   Common Stock 12/31/2017   F   14,162 (2) D $ 64.27 136,235 D   Common Stock 12/31/2017   A   7,281 (4) A $ 0 143,516 D   Common Stock 12/31/2017   F   4,000 (2) D $ 64.27 139,516 D   Common Stock               84,983 I by GRAT Common Stock               3,368 I by Trust

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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
DAMERIS PETER T ON ASSIGNMENT, INC. 26745 MALIBU HILLS ROAD CALABASAS, CA 91301	X		Chief Executive Officer

Signatures

By: Jennifer Painter, CLO For: Peter T. Dameris		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, achievement of the performance target related to these shares was certified. 25,773 shares were released on December 31, 2017. 25,773 shares will vest on January 2, 2019 and 25,773 shares will vest on January 2, 2020, subject to continued service to the issuer by the executive officer through such date.
(4)	The acquired shares are the portion of a performance award granted to the executive officer pursuant to his employment agreement that vested upon certification of performance targets on December 31, 2017.

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