He began in theatre which involved a largely solitary writing process, then moved into film where he collaborated with director Rob Reiner and screenwriter William Goldman, and eventually worked in television where he collaborated very closely with director Thomas Schlamme for nearly a decade on the shows Sports Night, The West Wing and Studio 60 on the Sunset Strip; he now moves between all three media.
Započeo je u kazalištu gdje je scenarije pisao uglavnom sam, a zatim je prešao na film gdje je surađivao s redateljem Robom Reinerom i scenaristom Williamom Goldmanom te naposljetku i na televiziju gdje je gotovo cijelo desetljeće vrlo usko surađivao s redateljem Thomasom Schlammeom na serijama Sports Night, Zapadno krilo i Studio 60 na Sunset Stripu.