The darkly comic August drama is a large ensemble piece (with three sisters at its core) set in a rambling house in Oklahoma. Letts (Who's Afraid of Virginia Woolf?) also penned the screenplay. John Wells (TV's "E.R." and "Shameless") directed the film adaptation. It will debut in theatres Dec. 25.

Oscar winner Roberts ("The Normal Heart," "Erin Brockovich") plays Barbara, the oldest Weston daughter, with Streep ("The Devil Wears Prada," "The Iron Lady") as cancer-stricken drug addict Violet Weston.

The cast also features Sam Shepard (Heartless), Oscar nominee Juliette Lewis, Ewan McGregor (West End's Little Malcolm and His Struggle Against the Eunuchs, "Moulin Rouge"), Olivier Award winner Benedict Cumberbatch (Frankenstein, "Sherlock"), Tony nominee Margo Martindale (Cat on a Hot Tin Roof), Oscar winner Chris Cooper ("Adaptation"), Dermot Mulroney ("My Best Friend's Wedding") and Oscar nominee Abigail Breslin (The Miracle Worker, "Little Miss Sunshine").

The Weinstein Company film is a Jean Doumanian / Smokehouse production produced by George Clooney and Grant Heslov, Jean Doumanian and Steve Traxler. Claire Rudnick Polstein is the executive producer.