A biography of Niels Bohr is not so much the record of a man as a history of our time. From 1911 to 1961 Bohr stood at the very center of the creation of atomic and nuclear physics. He personally contributed a theory of atomic structure, the theory of complementarity, and a theory of nuclear structure. Even more important, his institute for physics served as the communications center for physicists the world over. As director, Bohr figured significantly in most of the major developments in physics, not the least of which was the atomic bomb, which threw Bohr into the world of international politics, where he argued for a policy on atomic energy which unfortunately has never been adopted. Ruth Moore's biography records these activities with clarity and vigor. She properly emphasizes the scientific, which she explains in easily understood terms, but she mars her exposition with melodramatically imaginative interruptions. Nevertheless, the biography remains a sound introduction to modern physics and an exciting testimony to a great man.