William A. “Willie” Fowler was a Nobel Prize-winning physicist at Caltech, who knew J. Robert Oppenheimer from before the war. In this interview, he talks about how Oppenheimer and his “school” of students and post-docs would travel each year from the University of California, Berkeley to Caltech, where Oppenheimer had an appointment on the faculty. He describes how Oppenheimer’s theoretical knowledge and perspective supplemented the experimental research being conducted at Caltech, including Fowler’s own. He also talks about the lives and careers of other physicists who interacted with Oppenheimer in Pasadena, including Charles Lauritsen, Richard Tolman, and Robert Millikan. The interview concludes with a discussion of Fowler’s friendship with Frank and Jackie Oppenheimer.