Close relationships play a vital role in human health, but much remains to be learned about specific mechanisms of action and potential avenues for intervention. This article provides an evaluation of research on close relationships processes relevant to health, drawing on themes from major relationship science theories to present a broad conceptual framework for understanding the interpersonal processes and intrapersonal pathways linking relationships to health and disease outcomes. The analysis reveals that both social connection and social disconnection broadly shape biological responses and behaviors that are consequential for health. Furthermore, emerging work offers insights into the types of social dynamics that are most consequential for health, and the potential pathways through which they operate. Following from this analysis, the authors suggest several research priorities to facilitate the translation of discoveries from relationship science into relationship-based interventions and public health initiatives. These priorities include developing finer grained theoretical models to guide research, the systematic investigation of potential mediating pathways such as dyadic influences on health behavior and physiological coregulation, and taking into account individual differences and contextual factors such as attachment style, gender, socioeconomic status, and culture. In addition, a pressing need exists for laboratory and field research to determine which types of interventions are both practical and effective.