Research into obsessive—compulsive disorder (OCD) is advancing on many fronts: from genetics to phenomenology, to neuroimaging, to treatment by medication and psychological approaches including some guided by computer. Much of the recent progress made is detailed in this encyclopaedic volume. It is edited by three of the leading workers in the field. All but two of the 43 contributors to its 30 chapters are from the USA. The majority of those authors are from the east coast with far the greatest cluster from the Massachusetts General Hospital, Boston. Contributions are of a high order, often with detailed references to 100-200 or more articles.

Various chapters in this massive tome cover the clinical picture — epidemiology, clinical aspects, features in juveniles, personality disorders and OCD, pregnancy and OCD, so-called OCD spectrum disorders (Tourette's syndrome, trichotillomania), pathophysiology and assessment. Half the text reviews treatment by medication, behavioural and cognitive methods (including group and family issues, when using those methods), neurosurgery, and points to be taken into account with religious patients. There are detailed guides to practical clinical management with case examples. Two appendices are guides for consumers in readable style, one for patients and another for parents of children and adolescents with OCD. A contact list of support groups in the USA runs to 50 pages and in other countries to seven pages. Commonly-used rating scales are reprinted.

Being really several books in one, the volume's next edition could ease navigation so that each kind of reader could quickly look up what interests them in particular. Adding an author index would enable researchers to get to descriptions of particular studies. Editorial summaries of various parts of the volume would be helpful. Patients and their relatives would benefit from having more front-end highlighters to what might interest them within the mass of material; perhaps the main consumer-relevant parts could be pulled together into one section. It is surprising that the index does not include self-help, given that one of the editors, Lee Baer, has written an excellent popular guide on the subject.

This compendium is a notable feat and is an essential reference work for all libraries and serious researchers. It brings into one volume a huge amount of information relevant to OCD, especially that from an American perspective, for researchers, clinicians, patients and their families.