In this interview, David Zierler, Oral Historian for AIP, interviews Marvin Cohen, University Professor of Physics at Berkeley. Cohen recounts his childhood in Montreal and then San Francisco, and he describes his early love of science and informal experimentation. He describes his undergraduate experience at Berkeley and his decision to pursue graduate work at the University of Chicago, where he worked with Jim Phillips and conducted research in optical spectra and hexagonal semiconductors. Cohen discusses his work with Phil Anderson at Bell Labs on superconductivity at low temperatures. He describes the sequence of events leading to him joining the faculty at Berkeley and discusses his appointment at Lawrence Berkeley Lab and his efforts to foster research in condensed matter physics. Cohen describes his mentoring and teaching philosophy, and he explains his process that would help him decide what research projects to take on. He describes some of the philosophical and spiritual implications in thinking about physics over the course of a lifetime, and he explains the feeling of achieving "eureka moments. At the end of the interview, Cohen explains the questions in physics that continue to captivate his imagination.