X0303 4 2010-03-02 0 0000890564 ON ASSIGNMENT INC ASGN 0001021462 DAMERIS PETER T ON ASSIGNMENT, INC. 26651 WEST AGOURA ROAD CALABASAS CA 91302 1 1 0 0 President & CEO Common Stock 2010-03-02 4 S 0 8775 6.95 D 603102 D Common Stock 2010-03-02 4 S 0 5278 7 D 597824 D Common Stock 2010-03-02 4 S 0 315 7.01 D 597509 D Common Stock 2010-03-02 4 S 0 84 7.02 D 597425 D Common Stock 2010-03-02 4 S 0 1644 7.05 D 595781 D Common Stock 2010-03-02 4 S 0 700 7.1 D 595081 D Common Stock 2010-03-02 4 S 0 313 7.11 D 594768 D Common Stock 2010-03-02 4 S 0 200 7.13 D 594568 D Common Stock 2010-03-02 4 S 0 200 7.14 D 594368 D Common Stock 2010-03-02 4 S 0 100 7.16 D 594268 D Common Stock 2010-03-02 4 S 0 137 7.17 D 594131 D Common Stock 2010-03-02 4 S 0 200 7.18 D 593931 D Common Stock 2010-03-02 4 S 0 300 7.19 D 593631 D Common Stock 2010-03-02 4 S 0 300 7.2 D 593331 D Common Stock 2010-03-02 4 S 0 506 7.21 D 592825 D Common Stock 2010-03-02 4 S 0 100 7.22 D 592725 D Common Stock 2010-03-02 4 S 0 200 7.23 D 592525 D Common Stock 2010-03-02 4 S 0 100 7.24 D 592425 D Common Stock 2010-03-02 4 D 0 1019 6.95 D 591406 D Common Stock 2010-03-02 4 D 0 885 6.95 D 590521 D Executive officer elected to satisfy tax withholding obligations upon vesting by having On Assignment, Inc. withhold a number of vested shares equal to that of the employee's tax liability. Peter T. Dameris 2010-03-03