This handbook brings together the latest thinking on the scientific study of closeness and intimacy from some of the most active and widely recognized relationship scholars in social and clinical psychology, communication studies, and related disciplines. Each contributing author defines their understanding of the meaning of closeness and intimacy; summarizes existing research and provides an overview of a theoretical framework; presents new ideas, applications, and previously unstated theoretical connections; and provides cross-references to other chapters to further integrate the material. The Handbook of Closeness and Intimacy will be of interest to researchers, practitioners, and students from social, clinical, and developmental psychology; family studies; counseling; and communication.