Married men and women live longer lives than those who are not married. Transitions into marriage reduce the risk of dying, and transitions out increase it. In this lecture, I examine the link between marriage and health that underlies these differentials in mortality. I assess the relationship between marriage and three key dimensions of health: physical health; emotional well-being; and, cognitive function. I argue that the social institution of marriage changes the choices and behaviors of individuals in ways that foster good health and long life. I elaborate on this argument to include family more generally, in particular those with whom one lives. I argue that family members living together provide resources to each other, but also make demands.