Especially the past two decades have seen renewed interest in the vasculitides. In this volume an international expert group presents the current state of knowledge and concentrates on principles of immune modulating therapy. Drawing from their work in rheumatology, nephrology, internal medicine, connective tissue disease and clinical immunology, they present new concepts in classificiation, diagnosis and pathophysiology of the vasculitides. Evidence from experimental and clinical trials is reviewed, as well as the outlook for further research.