This book addresses the urgent need for a large and systematic analysis of current interdisciplinary (ID) research and practice. It demonstrates how ID is essentially a cognitive phenomenon, something different from the frivolous and inconsequential attempt of trying to overcome the disciplinary competencies and exigencies. By ID, the authors show that it is a manifestation of the transversal rationality that underlies current scientific activity. It is the very progress of specialized disciplines that requires interdisciplinary new research practices and new forms of articulation between domains, something that has a strong impact on the traditional disciplinary structure of scientific and educational institutions.  Divided into two parts, the book presents a conceptual framework as well as several case studies on ID practices. The book aims at covering three main themes. It contributes to the stabilization of ID meaning and characterizes the main ID theorizations whichhave been proposed until now. It builds an innovative and broad understanding of the several ID determinations as an essentially cognitive phenomenon and of its institutional implications at the level of disciplinary structures and curricular organization. Finally, it distinguishes and maps the diversity of ID procedures and practices which are being used and tested by contemporary scientific and educational institutions. This book is addressed to philosophers, scientists and every one interested in science production and reproduction, including science teaching.