Work at Massachusetts Institute of Technology Radiation Laboratory. Significant contributions to solid state physics. The interview deals briefly with Purcell's early acquaintance with Karl Lark-Horovitz at Purdue, while Purcell was an undergraduate electrical engineering major there. The bulk of the interview concerns Purcell's work at the MIT Rad Lab during World War II: how he started working there in 1940, his work with the magnetron group, the problems with the transmit receive switch, theory vs. experiment at the Rad Lab, the Steering Committee, work with the propagation group, the 1.25 cm radar fiasco, design of permanent magnets, postwar applications of Rad Lab research, and relations with British engineers. Purcell then discusses the influence of the Rad Lab on his subsequent career, his work with R. V. Pound, and H. C. Torrey at Harvard on NMR and the 21 cm line of hydrogen, and postwar uses of microwaves for physics research.