K. Warner Schaie, a pioneer in the study of gerontology, has written a monumental work representing his life-time contribution to the study of aging. The book analyzes the Seattle Longitudinal Study, which Professor Schaie began as a graduate student in the 1950's. Schaie's early work indicated that the popular notion of intelligence was simplistic and that there are many variations in terms of when intelligence peaks and declines, as well as many different factors that affect a person's intelligence. Important practical questions are raised: at what age do developmental peaks occur, and what are the generational differences and within-generation age changes; how do you establish sufficient competence for independent living? Intellectual Development in Adulthood should be read by all gerontologists and anyone concerned with aging and development.