The daughter of John Strong Perry Tatlock, a prominent Old English philologist and an expert on Geoffrey Chaucer, Tatlock was a graduate of Vassar College and the Stanford Medical School, where she studied to become a psychiatrist. Tatlock began seeing Oppenheimer in 1936, when she was a graduate student at Stanford and Oppenheimer was a professor of physics at the University of California, Berkeley. As a result of their relationship and her membership of the Communist Party, she was placed under surveillance by the FBI and her phone was tapped.