Obsessive-compulsive disorder is probably the psychiatric disorder for which most significant progress has been made on the last 20 years concerning pharmacologic and psychotherapeutic interventions. A number of studies have shown that OCD is much more prevalent than previously thought, occurring in an estimated 2% of the adult population around the world. A serious discrepancy still exists between research evidence and clinical practice and an update of this evidence and an international debate on it, as provided by this volume, is long overdue. This revised edition provides vital information on a considerably underdiagnosed condition.