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. Sure to be debated on talk shows and in living rooms, Vaillant’s definitive and inspiring book is the new classic account of how we live and how we can live better. It will receive massive media attention, and with good reason: we have never seen anything like it, and what it has to tell us will make all the difference in the world.

At a time when many people around the world are living into their tenth decade, the longest longitudinal study of human development ever undertaken offers some welcome news for the new old age: our lives continue to evolve in our later years and often become more fulfilling than before.

Begun in 1938, the Grant Study of Adult Development charted the physical and emotional health of over two hundred men, starting with their undergraduate days. The now-classic Adaptation to Life reported on the men’s lives up to age fifty-five and helped us understand adult maturation. Now George Vaillant follows the men into their nineties, documenting for the first time what it is like to flourish far beyond conventional retirement.

Reporting on all aspects of male life–including relationships, politics and religion, coping strategies, and alcohol use–Triumphs of Experience shares a number of surprising findings. For example, the people who do well in old age did not necessarily do so well in midlife and vice versa. While the study confirms that recovery from a lousy childhood is possible, memories of a happy childhood are a lifelong source of strength. Marriages bring much more contentment after age seventy, and physical aging after eighty is determined less by heredity than by habits formed prior to age fifty. The credit for growing old with grace and vitality, it seems, goes more to ourselves than to our stellar genetic makeup.