Recent research has shown that emotion understanding (EU)—the capacity to understand the nature, causes, and consequences of emotions—plays a crucial role in the development of emotional, social, and cognitive competences. However, there are still many unanswered questions about the extent to which EU facilitates children’s cooperative problem-solving in educational settings. For instance, it is not yet clear how understanding emotions positively impacts children’s interaction both when they play freely with peers and when they are engaged in problem-solving tasks. In addition, there is no conclusive answer about whether the impact of EU on cooperative problem-solving varies depending on children’s age. This chapter aims to address this shortfall. Building on empirical findings, the usefulness of EU for children engaged in different types of cooperation (dyadic, triadic, free play), and at different ages (from toddlerhood to middle childhood) is discussed.