Introduction -- Statement of the problem -- Administrative history up to December 1941 -- Progress up to December 1941 -- Administrative history 1942-1945 -- The metallurgical project at Chicago in 1942 -- The plutonium production problem as of February 1943 -- The plutonium problem, January 1943 to June 1945 -- General discussion of the separation of isotopes -- The separation of the uranium isotopes by gaseous diffusion -- Electromagnetic separation of uranium isotopes -- The work on the atomic bomb -- General summary.