In this interview, David Zierler, Oral Historian for AIP, interviews Marc Kastner, Donner Professor of Physics at MIT and senior science advisor to the Science Philanthropy Alliance. Kastner explains the nomenclature transition from solid state to condensed matter physics, and he surveys the interplay between theory and experiment in his field. He recounts his childhood in Ottawa and the influence of his father, who was an experimental physicist, and he explains the opportunities that led to his admission to the University of Chicago. Kastner explains his decision to remain at Chicago for graduate school to work under the direction of Hellmut Fritzsche on optical properties of semiconductors under pressure. He discusses his postdoctoral appointment at Harvard to work with Bill Paul on amorphous silicon, and his connection to David Adler who facilitated his faculty appointment at MIT. Kastner describes his work on amorphous semiconductors and transient excitation and his collaboration with Bob Birgeneau on high Tc. He discusses Joe Imry’s work on heterostructures and subsequent research on the Kondo effect, and how he came to understand the significance of his discovery of the single-electron transistor. Kastner discusses his tenure as department chair, director of MRSEC, and dean of science, and he explains his decision to retire and to join the Science Philanthropy Alliance. He describes his current work with his former student David Goldhaber-Gordon and his excitement over the current research on twistronics. At the end of the interview, Kastner reflects on the role of luck in his career, the centrality of technological advance in his research and what we can learn about physics more broadly as a result of the single-electron transistor.