Yrj� Engestr�m earned his Ph.D. from the University of Helsinki in 1987. He is a Professor of Adult Education and Director of the Center for Research on Activity, Development and Learning (CRADLE) at the University of Helsinki. He is Professor Emeritus of Communication at the University of California, San Diego, where he also served as Director of the Laboratory of Comparative Human Cognition from 1990 to 1995. Engestr�m applies and develops cultural-historical activity theory as a framework for the study of transformations and learning processes in work activities and organizations. He is widely known for his theory of expansive learning and for the methodology of developmental work… research.