This volume is the outcome of a long and passionate debate about two pivotal figures in psychology: Jean Piaget and Lev Vygotsky. The occasion was a week-long advanced course held at the Jean Piaget Archives in Geneva. The most interesting outcome of the meeting is that, in spite of differences in aims and scope (epistemogenesis versus psychogenesis), in units of analysis (events versus action) and in social content (Swiss capitalism versus Soviet communism), both Piaget and Vygotsky reached a similar conclusion: knowledge is constructed within a specific material and social content. Moreover, their views complement each other perfectly: where Vygotsky insists on varieties of psychological experiences, Piaget shows that out of diversity grows universality, so much so that the more communist of the two is not necessarily the one who was so labelled. This book is not only of interest to developmental, social and learning psychologists, but also deals with issues pertinent to education, epistemology, language, thought and cognition, anthroplogy, and philosophy. Its clear presentation should also make it of interest to the general reader.