A public symposium commemorating the fortieth anniversary of the first controlled, self-sustaining nuclear chain reaction achieved by Enrico Fermi and his colleagues on December 2, 1942 at the University of Chicago. The purpose of the symposium is to explore the scientific and political history of the Fermi experiment and to address the benefits and problems that have resulted. The symposium is divided into four sessions. Session I: History of the Chain Reaction - chaired by Eugene Wigner; speakers include: Robert G. Sachs, Alice Kimball Smith and Edward Levi. Session II: Peaceful Uses I - chaired by Jeremy Bernstein; speakers include: D. Allan Bromley and Henry S. Kaplan. Session III: Peaceful Uses II, Nuclear Power - chaired by Glenn Seaborg; speakers include: Alvin Weinberg, Walter Massey, Albert Carnesale, Frank von Hippel, Hans Bethe and John A. Simpson. Session IV: Control of Nuclear Armaments - chaired by W. K. H. Panofsky; speakers include: Marvin L. Goldberger, Michael M. May, Richard Garwin and Hans Bethe.