A graduate from SUNY Purchase, his alumni from the film and acting departments became known as The Purchase Mafia. Although Leiner did not graduate from either of these departments, he was friendly with Bob Gosse and other Purchase film makers.
It was these associations which led to his directorial feature debut, Layin' Low (1996).
He made his film debut with the award-winning short, Time Expired (1992), starring John Leguizamo.
Leiner then took the next few years to explore the world of television and directed a number of episodes for series such as Sports Night, Felicity, Strangers with Candy, Party of Five, Freaks and Geeks and Gilmore Girls. He also directed the documentary/drama telefilm, Flashback, which was a segment of the Cable Ace-nominated HBO production Faces of Addition.
For the start of the new millennium, Leiner returned to film with the bizarre comedy, Dude, Where's My Car (2000) starring Ashton Kutcher and Sean William Scott.
He spent the next few years directing episodes of series such as Everwood, Go Fish, The Mind of the Married Man, Maybe It's Me and The Tick. Leiner segued back to film with another oddball buddy comedy, Harold and Kumar Go to White Castle (2004).
Harold and Kumar Go to White Castle (2004)
Dude, Where's My Car? (2000)
Layin' Low (1996)