Greenfield directed the pilot episode of the television series Aliens in America and produced the film Role Models.
Adam Sandler and producers, Todd Garner and Greg Silverman, saw an early cut of the short and gave Greenfield his first opportunity to direct a studio feature called The Animal starring Rob Schneider.
Immediately after The Animal, Greenfield went back to creating and directing his own material with the coming-of-age film, The Girl Next Door.
At New Regency, Greenfield created a few of his passion projects, including the comedy, Role Models, which he produced for Universal Pictures.
Greenfield was then approached by producer Molly Smith to direct the film adaptation of the best-selling novel, Something Borrowed.