Greenland graduated from Scarsdale High School, received a BA from Connecticut College and an MFA at NYU.
Before becoming a full-time writer he worked as a construction worker, lobster fisherman, and in the early 1980s, sold cable television subscriptions door-to-door in Los Angeles.
He later worked on several projects with comedian Richard Belzer, sold jokes to Joan Rivers and wrote a spec television script that came to the attention of Norman Lear who hired him to work on the ABC series AKA Pablo, a sitcom about an Hispanic family starring Paul Rodriguez.
Greenland subsequently moved back to New York from Los Angeles, where he began to write screenplays and plays.
In 1995, Greenland wrote the screenplay for the New Line hip-hop comedy, Who's The Man?, starring Dr. Dre and Ed Lover and directed by Ted Demme.