Recent studies have examined whether values change across time. The present study investigates both rank-order stability and mean-level differences in core values—and whether age and sex moderate stability and change—over 3 years using a national probability sample (from 25 to 75 years; N = 3,962). Value priorities were highly stable, except for Conservation values among women, which peaked in stability at age 50 and decreased afterward. Older adults and women placed greater emphasis on values relating to the welfare of others and preservation of traditional practices and stability (Self-Transcendence and Conservation values). Younger individuals and men tended to more highly value the pursuit of status and power, and independent thought and behavior (Self-Enhancement and Openness to Change). The results are consistent with a life span perspective on values development and indicate values may change slowly throughout life as a reflection of biological and psychological maturation.