This book is a collection of the major scientific papers of Sir Rudolf Peierls (1907-95), including the Peierls-Frisch Memoranda of 1940 on the feasibility, and the predicted human effects, of an atomic bomb made of uranium-235. His papers range widely in topic. They include much on the fundamentals of solid state physics, the thermal and electric conductivity of materials as a function of temperature T (especially T� 0), the interpretation of the de Haas-van Alphen effect observed for a metal in a magnetic field, and the basics of transport theory. Many are on problems in statistical mechanics, including his constructive paper demonstrating the existence of a phase transition for Ising's model for a two-dimensional ferromagnet. In nuclear physics, they include the first calculations (with Bethe) on the photo-disintegration of the deuteron (made in response to a challenge by Chadwick), the Kapur-Peierls theory of resonance phenomena in nuclear reactions, the Bohr-Peierls-Placzek continuum model for complex nuclei (which first explained the narrow resonances observed for low energy neutrons incident on very heavy nuclei), and the Peierls-Thouless variational approach to collective phenomena in nuclei. Several of Peierls's wartime papers, now declassified, are here published for the first time.Brief commentaries on most of the papers in this book were added by Peierls, to indicate subsequent developments and their relationship with other work, or to correct errors found later on. A complete bibliography of his writings is given as an appendix.