Perhaps more than any other social theorist in recent history, Niklas Luhmann's work has aroused extreme, and often antagonistic, responses. It has generated controversies about its political implications, its resolute anti-humanism and its ambitious critique of more established definitions of society, social theory and sociology. Now, however, a steadily growing number of scholars working in many different disciplines have begun to use aspects of Luhmann's sociology as an important methodological stimulus and as a theoretical framework for reorientating their studies. This collection of essays includes critical and reconstructive contributions by a number of distinguished social theorists, political theorists, legal scholars and empirical sociologists. Together, they provide evidence of Luhmann's extensive and diverse relevance to the issues facing contemporary society, and, at the same time, they enhance our understanding of the challenges posed by his theoretical paradigm to more traditional conceptions of social theory.