Ossana first read the Annie Proulx short story Brokeback Mountain in the October 13, 1997 issue of The New Yorker magazine. She immediately urged her writing partner McMurtry to read it and asked him if he felt they could write a screenplay based upon the story. McMurtry agreed they could. They wrote Proulx asking her for an option to the short story in order to write a screenplay. Proulx replied that although she did not see the potential for a movie in the story, she would agree to their option. Ossana and McMurtry proceeded to write the script, which they completed in early 1998. Ossana's and McMurtry's screenplay for Brokeback Mountain won the Academy Award for Best Writing (Adapted Screenplay) as well as the Golden Globe Award for Best Screenplay and Writers Guild of America Award. Ossana, a producer on the film, also won the Golden Globe Award for Best Drama. The film was released in the United States in December 2005. Brokeback received widespread critical acclaim and it won the Golden Lion (Best Film) award at the Venice Film Festival and the Golden Globe Award for Best Picture - Drama. Ossana and McMurtry also won the Golden Globe Award for Best Screenplay for Brokeback Mountain. As a producer, Ossana joined cast and crew during the three months of shooting in Canada.

Ossana was born to an Italian immigrant father and raised in St. Louis, Missouri. She attended Eastern New Mexico University in Portales, New Mexico and has lived in Arizona since 1977.

Academy Awards

• 2005: Best Film (nominated), Brokeback Mountain
• 2005: Best Screenplay - Adapted, Brokeback Mountain

BAFTA Film Awards

• 2005: Best Film, Brokeback Mountain
• 2005: Best Screenplay - Adapted, Brokeback Mountain

Golden Globe Awards

• 2005: Best Screenplay - Adapted, Brokeback Mountain
• 2005: Best Drama Brokeback Mountain

PGA Awards

• 2005: Best Film, Brokeback Mountain

WGA Awards

• 2005: Best Screenplay - Adapted, Brokeback Mountain