The play centers on a deaf man born into a hearing family who meets a young woman on the brink of deafness, which changes his and ultimately his family's outlook.
Still will replace Jeff Perry in the role of Christopher beginning July 1. Westrate, winner of a 2012 Special Drama Desk Award for his versatility in the 2011-2012 season, will temporarily assume the role of Daniel while Will Brill takes a leave of absence from May 30 - July 1.
The cast also features Russell Harvard, Susan Pourfar, Gayle Rankin, and Mare Winningham.
Tribes has garnered 20 awards nominations and was declared "Best Foreign Play" by the New York Drama Critics Circle and "Best New Play" by the Off-Broadway Alliance.