This volume presents a rich overview of current research on activity theory in different parts of the world. It is divided into five parts: (I) Theoretical Issues, (II) Language, Thought and Development, (III) Play, Learning and Education, (IV) Work and Technology, (V) Issues of Therapy. The volume introduces the reader to the conceptual foundations and contemporary debates in activity theory, and it lays out the landscape of empirical research directions and practical applications in different countries.