This booklet contains personal reflections by scientists and engineers who made significant contributions to the development of nuclear fission for weapons and power generation. The collection originated at a session of the American Nuclear Society's 1982 winter meeting, and includes short presentations by Clarence Larson, Eugene Wigner, Isidor Rabi, Kenneth Nichols, Crawford Greenewalt, Manson Benedict, Henry Smyth, and John Simpson. All but one of the presentations deal with the Manhattan Project. The final chapter discusses the history of the Shippingsport reactor, the first facility to produce commercial nuclear power.