The unfolding of our lives continues across the life span. It is, however, more difficult to generalize about adulthood stages than about life’s early years. If you know that James is a 1-year-old and Jamal is a 10-year-old, you could say a great deal about each child. Not so with adults who differ by a similar number of years. The boss may be 30 or 60; the marathon runner may be 20 or 50; the 19-year-old may be a parent who supports a child or a child who receives an allowance. Yet our life courses are in some ways similar. Physically, cognitively, and especially socially, we differ at age 50 from our 25-year-old selves. In the discussion that follows, we recognize these differences and use three terms: early adulthood (roughly twenties and thirties), middle adulthood (to age 65), and late adulthood (the years after 65). Within each of these stages, people will vary widely in physical, psychological, and social development.