The investigations within this volume comprise a selection of seminal and influential articles and critical commentaries that contribute to an understanding of concepts and themes central to the field of Computer-Supported Collaborative Learning, as well as reflections on past and potential achievements of the field. They include 12 important theoretical articles from the international CSCL journal that expand our understanding of social cognition. They also include 11 recent essays by the editor, documenting theoretical conceptualizations and exemplary instances of collaborative learning. The volume begins with two new reflections on the vision and theory that result from this research.