Developmental research and educational practice involve conversations between children and adults. The conversational aspects of these situations have rarely been occasions for reflection. Discrepancies between the child's expectations and the adult's intentions can lead to misunderstanding, for example, at school or during a research interview. Communication can only succeed when the interlocutors agree about the ground rules relevant to the situation. When researchers and educators communicate with children, it is advisable that they understand the children's perspective on the interaction. In this article I argue that analysing adult-child and child-child interactions are particularly informative for shedding light on children's perspectives. Methodological aspects of interaction research are discussed. An overview of my research shows that, by clarifying the rules and conventions of the interaction, adults may help children to perform successfully. My interaction studies of pretend play and of students' discussions at school demonstrate that children reflect on the rules of interaction and make efforts to construct the communication tools they need for participating as competent partners in interactions with others.