The story of the Los Alamos project to build the first atomic bombs has been told often. Why then another history of Project Y, as it was known during World War II? Three features distinguish this account: it is a history of the technical developments; it is based on the full complement of documents, both classified and unclassified, of wartime Los Alamos; and it explores for the first time the methodology by which researchers at Los Alamos succeeded in their wartime mission.

Unlike earlier histories of Los Alamos, this book treats in detail the research and development that led to the implosion and gun weapons; the research in nuclear physics, chemistry, and metallurgy that enabled scientists to design these weapons; and the conception of the thermonuclear bomb, the “Super.” Although fascinating in its own right, this story has particular interest because of its impact on subsequent developments. Although many books examine the implications of Los Alamos for the development of a nuclear weapons culture, this is the first to study its role in the rise of the methodology of “big science” as carried out in large national laboratories.

Our primary aim is to recount this technical history, but we have not ignored the social context entirely. Although we largely leave for other historians the problem of analyzing the social community at Los Alamos in wartime – for example, the role of women, of foreign scientists, and of military personnel – we do provide an abbreviated account of the establishment and early years of the unique community that grew around the Los Alamos Laboratory.