Drawing upon extensive literature on the importance of social relationships from across social science and health disciplines, we propose a strong conceptualization of social health as a dynamic and multifaceted construct with the ability to expand and focus theory, research and practice. We define social health as the perceived and actual availability and quality of one’s various social relationships. Using this conceptualization, we demonstrate how a tripartite model of health, situated within the human body (and mind), best explains well-documented interrelationships between physical, psychological and social aspects of health. In order to describe the utility and importance of social health, we discuss its significance to understanding and addressing population health concerns, especially health inequalities, as well as recent major global events, including the rise of “deaths of despair” and the COVID-19 pandemic. By renewing research on social health under the framework presented herein, scholars can unify disparate lines of work on constructs ranging from loneliness and social integration to close relationship quality and social capital. Moreover, we argue that adoption of the concept of social health is critical to the success of nations, states and health systems across societies in guaranteeing an optimal state of health for all.