This chapter provides an overview of what is currently known about human emotional crying. It begins with evolutionary and developmental considerations and considers antecedents of adult crying and how they differ across individuals, which is followed by a discussion of the main functions of tears and empirical findings on their intraindividual and interindividual effects. The chapter reviews the relationship of crying with mental and physical health and describes the limited available research on crying in the therapy context, which will set the stage for the remainder of this volume focused on tears in therapy. Charles Darwin discussed human tears in his seminal work, The Expression of the Emotions in Man and Animals (1872). Darwin observed a connection between emotional tears and suffering, as well as between tears and tender feelings, and addressed questions such as whether animals weep, developmental and cross-cultural aspects of crying, and frequent crying as a characteristic of melancholia.