Bosworth was the author of bestselling biographies on Montgomery Clift (1978), Diane Arbus (1984), Marlon Brando (2000) and Jane Fonda (2011). Her book, "Montgomery Clift: A Biography" explores how the actor's introverted approach to his craft influenced James Dean and many others. Bosworth, whose father had been Clift's lawyer in the late 1940s, had total access to Clift's family while doing research for the project. She also spoke to many of Clift's close friends and colleagues. Conversations between Bosworth and Brooks Clift appeared in Montgomery Clift's nephew documentary Making Montgomery Clift.