Michael J. Arlen, her husband, said that she died after a long illness.
For their work on “Silkwood,” Ms. Arlen and Ms. Ephron were nominated for an Academy Award for best original screenplay. (Horton Foote won the Oscar for “Tender Mercies.”)
In 1997, after a 16-year-old boy was fatally shot on a Harlem sidewalk while defending his sister from a criminal during the crack epidemic, Ms. Arlen joined Jamal Joseph, a film professor at Columbia, and others in founding the Impact Repertory Theater, a nonprofit performing arts group for teenagers in Harlem. She was also a major supporter of the Central Park Conservatory, and a board member and past president of the Alicia Patterson Foundation, which awards fellowships to working journalists.