Caplan was an associate at Harvard University's DuBois Institute, director of the Voices of Diversity Project, and a past Fellow at the Women and Public Policy Program of the John F. Kennedy School of Government at Harvard.
Previously she had been full professor of psychology, assistant professor of psychiatry, and lecturer in Women's Studies at the University of Toronto, as well as head of the Centre for Women's Studies in Education there, and was chosen by the American Psychological Association as an "eminent woman psychologist".
She was the author of The Myth of Women's Masochism, Don't Blame Mother, and a number of other books.
Her twelfth and final book was When Johnny and Jane Come Marching Home: How All of Us Can Help Veterans, which won the 2011 American Publishers Award for Professional and Scholarly Excellence in the Psychology category.
In her book, They Say You’re Crazy: How the Worlds most Powerful Psychiatrists Decide Who’s Normal, Caplan discusses the nature of diagnosis and how the DSM contributes to the unique faults of psychiatry.