Material artifacts playa prominent role in most social practices. Humans learn and develop not only in a world of social relationships but also in a world of things. In spite of the ubiquity of physical objects in all that we do, most theoretical accounts of learning and development downplay or even disregard the fundamental manner in which our actions, insights, and modes of knowing are dependent on familiarity with and use of things. By failing to consider the role of such resources in human activities, most theoretical perspectives simultaneously downplay the role of artifacts in the cumulation of knowledge and skills in society at large.