This new edition of Conceptual Developments of 20th Century Field Theories explores the conceptual foundations and historical roots of fundamental field theories. It also uncovers the underlying issues, logic and dynamics in fundamental physics. In response to new advances in the field over the past twenty years, the sections on gauge theory and quantum field theory have been thoroughly revised and elaborated. The chapter on ontological synthesis and scientific realism has also been reconsidered, now suggesting a new approach that goes beyond structuralism and historicism. Providing an integrated picture of the physical world, it is a valuable resource for theoretical physicists and philosophers of science with an interest in the development of twentieth century mathematical physics. It also provides professional historians and sociologists of science with a basis for further historical, cultural and sociological analysis of the theories discussed.