The research reported in this thesis originated in a project which aimed at describing the development of children's understanding of friendship. This project was construed as an exercise in social cognition from a Piagetian perspective. The results of empirical studies, however, led to the assumptions of this theoretical approach being questioned; in particular the paradigm of social cognition failed to offer any comprehension of friendship as socio-psychological reality. The second part of the thesis examines the theoretical problems of the 'social cognition' paradigm and outlines a theoretical perspective in which the cognition of social life may be approached frDm the perspective of genetic epistemology.