In this interview, David Zierler, Oral Historian for AIP, interviews Robert Cahn, Senior Scientist Emeritus at the Lawrence Berkeley Laboratory. Cahn recounts his childhood in the San Francisco area, and he describes his early interests in math and science, and he describes his undergraduate experience at Harvard, where he was influenced by Dan Kleppner and Ed Purcell. Cahn describes his summer internship at SLAC, and his travel experiences in Europe after graduating. He describes his decision to pursue graduate work at Berkeley and he explains the political tumult that had convulsed the campus in the late 1960s. Cahn discusses his work with Dave Jackson on Regge theory and his postdoctoral work at SLAC, which was focused on quark research. Cahn describes his work at the University of Washington, where he collaborated with Lowell Brown, and he explains his decision to join the physics faculty at University of Michigan, where he collaborated on several projects with Gordy Kane and where he became interested in parity violation in atoms. Cahn explains his decision to move to UC Davis, and he describes the opportunity at LBL that presented itself shortly thereafter. Cahn describes the way LBL has been integrated with the physics department at Berkeley, and he discusses his tenure as Director of the Physics division. At the end of the interview, Cahn describes LBL’s increasing involvement in cosmology, the fundamental discoveries that have been made over the course of his career, and he considers some of the philosophical or metaphysical issues that arise in investigating how the universe works.