This study investigated adulthood predictors of health-promoting behavior in later aging. The participants were 162 members of the Terman Study of the Gifted (Terman et al., 1925), who responded in 1999 at an average age of 86 to a mailout questionnaire which included questions concerning their positive health behavior. Adulthood variables were obtained for analysis from the study archives. Cross-sectional analyses showed that health-promoting behavior was related to perceived health and well-being in later aging. In longitudinal analyses, "easygoingness" in adulthood was positively related to positive psychosocial behavior and positive health practices, and neuroticism was negatively related to positive psychosocial behavior in later aging. Perceived health in adulthood was related to positive psychosocial behavior, exercise, physical recreation, and other positive health practices. Education, perceived health in adulthood, recalled importance in adulthood of success in sports before the age of 12, and interest in outdoor sports in early adulthood, as well as current health problems, were related to exercise and physical recreation in later aging. Gender played a moderating role in the prediction of positive psychosocial behavior, with the relationship of self-rated health in adulthood and recalled importance of success in sports before the age of 12 with positive psychosocial behavior being stronger for men than for women.