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 per cent 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. It provides accompanying commentaries by an outstanding line up of contributors; covers developments in diagnosis, therapy, prognosis, economic evaluation and quality improvement; and provides an unbiased and reliable reference point.