The papers of John Von Neumann (1903-1957) and Klára Dán Von Neumann-Eckart (1911-1963) span the years 1912-2000, with the bulk of the items concentrated in the period 1935-1963. The papers pertain primarily to John Von Neumann's life in the United States after he emigrated from Hungary to the United States in 1930 and to the work and family of his second wife and widow, Klára Dán, after her emigration in 1938. Featured is John's career as professor of mathematics at the Institute for Advanced Study in Princeton (1933-1957), adviser and commissioner on the United States Atomic Energy Commission (1952-1957), scientific consultant to government and industry, and author of works on various scientific topics. Also featured are their family relationships and Klára's career as a computer programmer. The collection consists of correspondence, memoranda, journals, speeches, articles and book drafts, notes, charts, graphs, patent, family papers, clippings, printed matter, photographs, and other material. The papers are organized into eight series: Family Papers, General Correspondence, Subject File, Speeches and Writings File, Addition I, Addition II, Addition III, and Oversize.

The Family Papers series consists chiefly of correspondence between John Von Neumann and family members. Of particular significance is the extensive correspondence between him and Klára Dán Von Neumann concerning professional and family matters.

The General Correspondence series contains John Von Neumann's incoming and outgoing correspondence with his colleagues at the Institute for Advanced Study, the Atomic Energy Commission and other government bodies, including the Los Alamos Scientific Laboratory, and various universities. Of special interest are an Albert Einstein letter and report on theoretical physics (1937). Other correspondents include Frank Aydelotte, Hans Albrecht Bethe, Garrett Birkhoff, S. Chandrasekhar, George Bernard Dantzig, P. A. M. Dirac, Carl Eckart, Enrico Fermi, Abraham Flexner, George Gamow, Kurt Gödel, Herman Heine Goldstine, Werner Heisenberg, L. van Hove, Cuthbert Hurd, Pascual Jordan, R. H. Kent, George B. Kistiakowsky, Oskar Morgenstern, J. Robert Oppenheimer, Rudolf Ortvay, Wolfgang Pauli, Marshall H. Stone, Lewis L. Strauss, Abraham Haskel Taub, Edward Teller, Stanislaw M. Ulam, Oswald Veblen, Warren Weaver, Hermann Weyl, Norbert Wiener, and Eugene Paul Wigner.

The Subject File documents all facets of John Von Neumann's career in the United States, reflecting his role in early computer and atomic research. The bulk of the series pertains to his work at the Institute for Advanced Study, including his tenure as director of the Electronic Computer Project. Other papers document Von Neumann's many consultantships. Of particular interest are files relating to his work at the United States Army Ballistic Research Laboratory in Aberdeen, Maryland.

The Speeches and Writings File reflects John Von Neumann's interest in numerous scientific and mathematical subjects. The series includes his early writings in quantum mechanics and logic, his writings on continuous geometries, operator theory, ballistic research, and his later works concerning computers. Also of note is his pioneering work on game theory. Throughout the Speeches and Writings File are evaluations of Von Neumann's work written after his death by his colleagues. Among the reviewers were Herman Heine Goldstine, Paul R. Halmos, and Abraham Haskel Taub.

Addition I to the papers consists of correspondence between John Von Neumann and Eva Aldor, other material relating to Eva Aldor and Peter Aldor, correspondence relating to the Poiseuille-type laminar flow, biographical information, a patent, photographs, and printed matter.

The bulk of Addition II was created by Klára Dán Von Neumann, who was one of the early computer programmers. In the general correspondence of Addition II is Klára's correspondence with many of the physicists and mathematicians documented in the General Correspondence series and their wives, including fellow programmers such as Francois Ulman. In the family correspondence of Addition II are letters spanning 1937-1954 between Klára and John Von Neumann. Also in the file are Klára's exchanges with John's brothers, Michael J. Neumann and Nicholas A. Vonneumann, and in Hungarian with members of Klára's own Dán family, including her mother, Kamilla Dán, and sister, Elizabeth Deg. Much of the Hungarian correspondence relates to getting Klára and then her family members, who were Jewish, out of continental Europe at the onset of World War II. A file relating to John Von Neumann's literary estate includes correspondence with Robert Maxwell, the proprietor of Pergamon Press and publisher of his collected works.

Addition III consists of draft chapters of Klára Dán Von Neumann's unpublished memoir, "Grasshopper in Very Tall Grass," related correspondence, and other assorted material.