This chapter examines the evidence for an effect of marital status on mental health, with a particular focus on the factors that identify who benefits from marriage, who suffers from marital dissolution, and under what circumstances. Studies of marital status differences in mental health commonly employ outcome measures of psychological distress and depressive symptoms. Several recent longitudinal studies have demonstrated that entering marriage is associated with increases in psychological well-being and declines in psychological distress. A growing body of research provides convincing evidence that the mental health benefits of marriage and the costs of marital dissolution vary greatly, depending on a range of individual, demographic, and relationship characteristics. These are commonly referred to as moderators of the relationship between marriage and mental health. Finally, it is important to remember that marriage and marital dissolution both involve a combination of rewards and strains.