The Fowler papers form a rich and important collection for the history of physics and astrophysics, as well as for the politics and sociology of science in the twentieth century. Included are working papers, correspondence, reprints, and biographical material. Of significance are materials relating to his mentor Charles C. Lauritsen from the 1920s and 1930s at Caltech, documents related to Caltech's World War II rocket project and his involvement in the war effort. Documentation also exists for Fowler's involvement in postwar defense work, particularly the study of strategic nuclear weapons know as Project Vista, and the creation of the Office of Naval Research.

Much of the correspondence is both incoming and outgoing and can be found in relevant sections throughout the collection in addition to the correspondence section. California Institute of Technology materials document his work there including teaching, Kellogg Radiation Laboratory, and the Physics, Mathematics and Astronomy (PMA) Division materials. Fowler and Caltech's work in World War II and its immediate aftermath are documented including the rocket project sponsored by the Office of Scientific Research and Development (OSRD) technical reports, correspondence, and administrative materials. Documented is his work with Professional Organizations and Government Agencies including American Physical Society, National Academy of Sciences, and the National Science Foundation's Nuclear Science Advisory Committee. Manuscripts include drafts, unpublished manuscripts, and manuscripts by others. The reprints include many but not all Fowler's publications. The technical files are divided into broad subjects including Nuclear Physics, Nuclear Astrophysics, the solar neutrino problem, stars and supernovae, cosmochronology. Biographical Materials include the Nobel Prize, oral histories and interviews. Photographic material includes photos, slides, films. Also included are certificates, honorary degrees, and medals.