P. A. M. Dirac was one of this century's most outstanding theoretical physicists. Among many fundamental advances, he formulated a fully relativistic theory of the electron, and predicted the existence of the positron. Dirac was awarded the Nobel Prize for Physics in 1933, at the age of just thirty-one. This volume brings together for the first time all of Dirac's scientific publications from 1924 until 1948, his most productive years. Each paper is reproduced in its original form and, for the few not in English, a matching translation is provided. Also included here are reset versions of Dirac's hitherto unpublished wartime research papers. This comprehensive collection will provide a valuable and convenient reference source, and will allow students of the history of science to trace the development of the ideas of one of the founders of quantum mechanics.