Known for penning plays like This is Our Youth and The Waverly Gallery, the latter of which was nominated for the Pulitzer Prize in 2001. Also known for his work in film, he directed the 2000 feature You Can Count On Me and the 2016 film Manchester By The Sea.
His first play, The Rennings Children, was chosen for the Young Playwright's Festival in 1982.
He worked as a speechwriter for the Environmental Protection Agency after graduating from NYU.
He married actress J. Smith-Cameron in 2000.
He co-wrote the screenplay for the 2002 film Gangs of New York, directed by Martin Scorsese.