Since the average ages of many industrialized nations' workers are increasing, it is important to know (1) the causes of employees' decisions to retire early and (2) the effects of retirement on the lives of retirees and on their employing organizations. The fields of gerontology and of social, clinical, and developmental psychology have investigated retirement, usually focusing on individual well-being as a criterion. Industrial/organizational psychology generally has not delved into the topic. A review of the empirical literature and theories regarding the two retirement issues leads to conclusions that are very tentative due to the nature of the research methods used until now. I/O psychologists have the opportunity to contribute to knowledge about retirement because of their dual interests in both individuals and organizations and because of their tradition of scientific rigor. Propositions are provided for future research.