Developmental studies are beginning to bring together previously separate areas of research on emotion and cognition, making this a particularly exciting time for a special issue of Cognition and Emotion focusing on developmental research. Three themes, each central in current developmental studies, are brought together in this special issue, in which leaders in developmental research describe their most recent studies. These themes are the nature and developmental course of children's understanding of emotion; the development of children's understanding of mind; and the influence of a range of socialisation experiences, including emotional expression, on children's social relationships and behaviour. The studies in this issue bridge the gaps between these domains: they illuminate the connections, but also show us some of the differences in the pattern of children's development in emotion and understanding. Cutting across the studies described are a number of common themes: an interest in individual differences; in using natural language data and observational methods as well as experimental approaches; in gender differences in emotional expression and experiences and their implications; and, perhaps most striking of all, in framing developmental questions in terms of both cognitive and emotional development. The generative potential of the research described is unquestionable and the innovative combinations of interest in both cognitive and emotional aspects of development greatly to be welcomed.