Joshua Lederberg's (1925-2008) path-breaking research into the molecular mechanisms of gene action made him one of the founders of molecular biology in the 1940s and 1950s. A prodigy who received the Nobel Prize at age 33, he helped lay the groundwork for genetic engineering, modern biotechnology, and genetic approaches to medicine. Interdisciplinary in his scientific interests and methods, Lederberg became a pioneer of space biology, and was instrumental in introducing computers and artificial intelligence into laboratory research and biomedical communication. As a postwar liberal with an abiding faith in the ability of government to improve society, secure peace, and protect the environment with the advice of scientific experts, Lederberg has served for over forty years on advisory commissions on science and health policy, space exploration, national security, and arms control.