Oscar rivals Brokeback Mountain and Crash have shared top honours at the Writers Guild of America awards.
Crash has won plaudits for its script about racial intolerance in LA
Ang Lee's cowboy romance, which leads the Oscar race with eight nominations, won the best adapted screenplay award.
Racial drama Crash, from the pen of director Paul Haggis, was named best original screenplay, by the group of US TV and film screenwriters.
Both films are emerging as frontrunners for the best picture Oscar, ahead of the Hollywood ceremony on 5 March.
Brokeback Mountain is adapted from a short story by Annie Proulx
Diana Ossana, who adapted Brokeback Mountain with fellow scriptwriter Larry McMurty, said she felt honoured to be in the same "stellar company" as fellow nominees.
The love story, which stars Heath Ledger and Jake Gyllenhaal, beat A History of Violence, Capote, Syriana and The Constant Gardener, from British screenwriter Jeffrey Caine, to scoop the award.
Crash, which has six nominations for this year's Academy Awards including best film and best director, is co-written by Haggis and Bobby Moresco.
"To say our script is any one bit better than the others is nuts," said Moresco, receiving his award at a ceremony in Los Angles on Saturday. "It's not a competition, and we all know it."
The first series of crash drama Lost won best drama at the Emmys
The film beat rivals including Cinderella Man, The 40-year-old Virgin, The Squid and The Whale and George Clooney's Good Night, and Good Luck.
Clooney and fellow screenwriter Grant Heslov were given an honorary award for a screenplay whose spirit embodies constitutional and civil rights issues.
The film, a homage to US broadcaster Edward R Murrow, centres on Murrow's on-air conflict with Senator McCarthy in the 1950s.
The Hollywood screenwriters also handed out awards for the best scripts in television, with Lost winning best drama series and Larry David picking up the best comedy series award for Curb Your Enthusiasm.