In this interview, David Zierler, Oral Historian for AIP interviews Siegfried Hecker, Professor Emeritus with the Department of Management Science and Engineering, and Senior Fellow, Freeman Spogli Institute for International Security and Cooperation, at Stanford University. Hecker recounts his family background as the child of ethnic Austrian and German parents who lived in Bosnia at the outbreak of World War II. He describes his family’s ordeal during the war and the circumstances surrounding his mother’s decision to move the family to the United States. Hecker recounts his experiences growing up in Cleveland and his decision to attend Case Tech for his undergraduate education. He explains his decision to switch his focus from physics to metallurgy, his formative summer at Los Alamos Lab before returning to Case for his Ph.D. work, and his decision to return to Los Alamos for postdoctoral research in metallurgy and elastic to plastic transitions. He describes his work at the General Motors Research Lab and his decision to return once again to Los Alamos, where he was assured he could focus on science and not management issues. Hecker explains how he became more involved in plutonium research and the various national security implications of this work. He describes his rise in the ranks at Los Alamos and how he became involved in national policy decisions in Washington. Hecker recounts the circumstances leading to being named director of Los Alamos, and he reflects on the challenges and opportunities he saw to improve the lab in this position. He provides an overview of nuclear weapons policy at the end of the Cold War and the renaissance in plutonium research in the 1990s. Hecker reflects on his decision to join the faculty at Stanford, and why he wanted to pursue matters of international security studies, and he describes his record of advisory work on nuclear verification in North Korea and elsewhere. At the end of the interview, Hecker describes his ongoing interest and research in metallurgy, and he reflects on how these interests bring him back full circle to the origins of his career.