Origin of interest in nuclear physics, discussions of compound nucleus, Copenhagen, 1936; work on interaction of evaporation and nuclear temperature, 1936; Breit-Wigner formula; application of evaporation model to nuclear reactions; postwar work in electrodynamics and nuclear reactions; relative merits of compound nucleus and shell models, 1950-51; explanation of independent particle motion by Pauli principle, 1951; estimates of shell model radiative transition probabilities; optical model and relation to compound nucleus models, 1953-55; emigration to U.S., 1937; initial impressions of American physics community; teaching and research at University of Rochester, 1937-43; visits to Cornell University; elaboration of evaporation model; effect of Bethe-Bacher-Livingston REV. MOD. PHYS. review articles, 1936-37; contact with physicists at American institutions; summer schools in U.S. and Europe; role of conferences; centers of nuclear physics research, 1930s; the atmosphere and social aspects of life at Los Alamos and subsequent effect on physics, 1943-47; effect of war work at MIT on electrodynamics and nuclear models, 1947-55; visits to Brookhaven; collective model; role of nuclear spectroscopy; origins of high-energy physics; relations among nuclear structure, meson physics, and field theory; current (1966) work in nuclear physics in Europe; the future of nuclear physics.