In recent years, emotion researchers have paid increasing attention to the functions that emotions service. This attention to function has been apparent in many disciplines and at many levels of analysis. From the most basic physiological symptom to the most overarching social structure, the effects of emotion, both on the emotional person and on others, are being recognized. The knowledge that has accumulated is substantial but is scattered among a variety of fields and literatures. This special issue summarizes the functional approach to emotion. The six articles that have been selected concentrate on the work of psychologists but include many of the other fields that have contributed to what is truly a multidisciplinary approach. The special issue opens with three foundational articles that discuss (a) the intrapersonal functions of emotions, (b) the social functions of emotions, and (c) the developmental functions of emotions. The next three articles focus on challenges to traditional functional accounts of emotions. These articles consider (d) emotion regulation, (e) emotions and psychopathology, and (e) negative affect and health.