CALABASAS, Calif.--(BUSINESS WIRE)--On Assignment, Inc. (NYSE: ASGN) will participate in the following conference in June of 2015: William Blair 35th Annual Growth Stock Conference on June 9, 2015, 7:30 AM (CDT) at the Four Seasons Hotel in Chicago. Representing On Assignment will be Peter Dameris, President and Chief Executive Officer; Ed Pierce, Chief Financial Officer; and Ted Hanson, Chief Financial Officer of Apex Systems, a division of On Assignment. A webcast will be available at http://