Close relationships are a vital part of people’s daily lives; thus family members, friends, and romantic partners play an integral role in people’s health and well-being. Understanding the ways in which close relationships both shape and reflect people’s health and wellness is an important area of inquiry. Showcasing studies from various disciplines that are on the cutting-edge of research exploring the interdependence between health and relationships, this collection highlights several relationship processes that are instrumental in the maintenance of health and the management of illness, including interpersonal influence, information management, uncertainty, social support, and communication. Although the existing health literature is rich with knowledge about individual and ecological factors that are influential in promoting certain health behaviors, the relationship scholars featured in this volume have much to contribute in terms of documenting the interpersonal dynamics that are involved in experiences of health and illness.