Do persons exposed to radiation suffer genetic effects that threaten their yet-to-be-born children? Researchers are concluding that the genetic risks of radiation are less than previously thought. This finding is explored in this volume about the children of atomic bomb survivors in Hiroshima and Nagasaki–the population that can provide the greatest insight into this critical issue. Assembled here for the first time are papers representing more than 40 years of research. These documents reveal key results related to radiation’s effects on pregnancy termination, sex ratio, congenital defects, and early mortality of children. Edited by two of the principal architects of the studies, J. V. Neel and W. J. Schull, the volume also offers an important comparison with studies of the genetic effects of radiation on mice. The wealth of technical details will be immediately useful to geneticists and other specialists. Policymakers will be interested in the overall conclusions and discussion of future studies.