Decades of research have demonstrated that normal aging accompanies cognitive change. Much of this change has been conceptualized as a decline in function. However, age-related changes are not universal. Oft-found decrements in older adult performance may be moderated by experience, genetics, and environmental factors. To date, cognitive aging has largely emphasized biological changes in the brain, with less evaluation of the range of external contributors to behavioral manifestations of age-related decrements in performance. The goal of this book is to examine cognitive aging through the lens of a life course perspective. Understanding cognition within the context of both the life span (aging) and the life course (experience) is a relatively new approach to the field of cognitive aging. However, the approach has already pushed the field forward in theoretically and practically important ways.