In recent years, the notion of communication contract has stimulated a lot of research in social developmental psychology as well as in education. This article presents two series of investigations using different methods for the study of the didactic and experimental contracts. The discussion focuses on some theoretical issues raised by these studies: the risk of sociological vs psychological reductionism, the risk of neglecting the specificity of cognitive activity and the risk of reifying the notion of context. Possible developments for future research will be suggested. The problem of the articulation between social, institutional and interactional contexts in the study of cognitive activity is a central argument.