Men in the United States suffer more severe chronic conditions and die 6 years younger than women. For all leading causes of death, and in every age group, men and boys have higher death rates than women and girls. Despite these risks, little is known about the gender-specific health and health care needs of men and boys. This multidisciplinary review provides an overview and summary of key determinants of the health and wellbeing of men and boys in the United States. Thirty key determinants of physical and mental health were identified from a review of literature and are summarized under the following four categories: behaviors of men and boys, health-related beliefs and the expression of emotions and physical distress, underlying factors that influence the health behaviors and beliefs of men and boys, and health care. The findings reported in this review suggest that men's greatest health risks are the result of modifiable factors, and that efforts to address these factors through practice, policy, and research could contribute to enhanced health conditions for men and boys, as well as to healthier families and communities.