The unique history of nuclear weapons and nuclear power have created a host of unintended knock-on consequences to individuals and societies across the world through their development and deployment. This paper reviews the cases of the atomic bombings of Hiroshima and Nagasaki and the nuclear accident at Chernobyl for long-term effects on human psychological and social processes in victims and their families. Key aspects to the psychology of the atomic bomb experience were the phenomenon of “silence” in survivors and an anxiety about the possible unknown health and genetic effects of exposure, with relatively few issues observed in descendants. Children, women, clean-up workers, and migrants are known to be vulnerable or at-risk populations for mental health issues in Chernobyl. Implications for future research in this domain are discussed.