Daniel Day-Lewis and Julie Christie have won best actor and actress at the Screen Actors Guild awards.
The Coen Brothers won the best film award for No Country For Old Men, strengthening their hopes for a win at next month's Oscars.
Day-Lewis dedicated the win for his role in There Will Be Blood to the actor Heath Ledger, who was found dead in New York last week.
Christie won for her portrayal of a woman facing dementia in Away From Her.
The SAG presentation was the first major Hollywood award show of the year not to be affected by the screenwriters' strike, the BBC's Peter Bowes reported from Los Angeles.
Unlike other award ceremonies, the show went ahead because the writers' union reached an agreement with the SAG to allow its members to take part.
The actors' union strongly supports the striking writers, who are demanding a new contract with royalty payments for DVD sales and internet downloads.
Tribute to Ledger
Without the threat of a picket line, the show attracted A-list stars, such as John Travolta and Tom Cruise.
Bardem said his award was "thoroughly unbelievable"
In his tribute to Ledger, Day-Lewis said he had been unique and perfect in Brokeback Mountain.
"That scene in the trailer at the end of the film is as moving as anything I think I've ever seen," he added.
Day-Lewis, who has joint British-Irish citizenship, won an Oscar in 1990 for My Left Foot. He was also nominated in 1994 for In the Name of the Father and in 2003 for Gangs of New York.
Christie was one of the few stars to mention the writers' dispute, the Associated Press notes.
"It's lovely to receive an award from your own union, especially at a time when we're being so forcefully reminded how important unions are," she said.
Spanish actor Javier Bardem won a SAG award for best supporting actor for his role as the psychopathic killer in No Country for Old Men.
"Thank you, guys, for hiring me, and thank you for taking the hard work of choosing the good takes instead of the ones where I really sucked," he said in his acceptance speech, addressing the Coen brothers.
The television category was dominated by mob drama The Sopranos.
James Gandolfini played mobster Tony Soprano in the hit series
The series, which ended last year, won the award for best ensemble in a drama series, and the show's main stars, James Gandolfini and Edie Falco, were named best actor and actress.
"This is our last official act as Sopranos together," Gandolfini said.
"Here's to you guys. Thank you very much. It's been 10 years. It's been an honour. That's all I can say."
The US version of The Office won the award for best cast in a comedy.