In an unprecedented series of studies, Harvard Medical School has followed 824 subjects -- men and women, some rich, some poor -- from their teens to old age. Harvard's George Vaillant now uses these studies -- the most complete ever done anywhere in the world -- and the subjects' individual histories to illustrate the factors involved in reaching a happy, healthy old age. He explains precisely why some people turn out to be more resilient than others, the complicated effects of marriage and divorce, negative personality changes, and how to live a more fulfilling, satisfying and rewarding life in the later years. He shows why a person's background has less to do with their eventual happiness than the specific lifestyle choices they make. And he offers step-by-step advice about how each of us can change our lifestyles and age successfully.