With Kennedy and Steven Spielberg, Marshall was one of the founders of Amblin Entertainment. In 1991, he founded, with Kennedy, The Kennedy/Marshall Company, a film production company which has a contract with DreamWorks Studios. Since May 2012, with Kennedy taking on the role of co-chair at Lucasfilm, Marshall has been Kennedy/Marshall's sole principal. Marshall has consistently collaborated with directors Steven Spielberg, Peter Bogdanovich and Robert Zemeckis.