This article offers an introduction to the journal's special issue on emotion cognition in adolescents and children. Emotion cognition refers to a variety of processes involved in the activation, modulation, and use of emotions in social transactions (Izard et al., 2001). These processes reflect interconnections and coordination of emotions and cognitive systems. A core component consists of knowledge of emotion expressions and of typical situational elicitors of expressions and feelings. For instance, expression knowledge allows a child to recognize facial cues of discrete emotions such as happy, sad, mad, and fear as well as to retrieve verbal labels in memory associated with the expressions. Emotion situation knowledge allows a child to infer and anticipate discrete emotions of others and of self from social cues. For instance, loss cues sadness, and intentional aggression against another person cues happiness--well, at least for some (for others, it cues anger). The studies in this issue demonstrate a broad range of approaches to examining emotion cognition in children and the relations of emotion knowledge to social exchanges and adjustment. Despite the clear and central role of emotion knowledge in framing interpretation of social events and in mediating access of emotion feelings and their behavioral expressions, developmental researchers have only recently begun to relate emotion knowledge to the processing of social information. With the mapping of normative development in emotion knowledge fairly complete, it is time to examine variation in such knowledge and its application in a systematic fashion. The studies in this special issue advance this goal. (PsycINFO Database Record (c) 2017 APA, all rights reserved)