In Developmental Influences on Adult Intelligence, Warner Schaie lays out the reasons why we should continue to study cognitive development in adulthood, and presents the history, latest data, and results from the Seattle Longitudinal Study (SLS), which now extends to over 45 years. From his work on the SLS, Schaie derived a conceptual model that he presents in this volume. The model represents his view on what influences cognitive development throughout the lifespan, and provides a rationale for the various influences that he investigated - genetic factors, early and current family environment, life styles, the experience of chronic disease, and various personality attributes. The data in this volume include the 1998 longitudinal cycle of the SLS. In light of both new data and revised analyses, psychometric and neuropsychological assessments have been linked in long-term data to aid in the early identification of risk for dementia in later life. Schaie also presents new data and conclusions on the impact of personality on cognition.