This is a thoughtful and probing book. At first, I wondered whether the evidence base for the various types of psychological therapy would be summarised. This approach is not taken. Instead, the nature of evidence itself is explored. It is intended to show that ‘evidence takes many forms in a psychologically complex field’ and to look at how evidence can be gathered and used across a range of practice, from the behavioural therapies to psychoanalysis. From the outset there is acknowledgement of the difficulty of applying an evidence-based model to the psychotherapies and an awareness that attitudes towards the scientific method can vary from ‘willing borrowing to deep distrust’.

The book follows on from a conference organised by the Royal College of Psychiatrists, the University Psychotherapy Association and the Association of University Teachers of Psychiatry. The contributors, 17 in total, come from a variety of specialist backgrounds, including law, sociology and philosophy as well as psychoanalysis, cognitive—behavioural therapy, psychology and psychiatry.

In the opening chapter, a professor of law discusses how the legal concept of evidence, grounded in the need to resolve a case (where establishing the truth may be a subsidiary consideration), differs significantly from scientific concepts regarding evidence. He contrasts the intense debate within the medical profession about what constitutes best-evidence practice with the almost ‘complete absence of discussion of best-evidence practice within the legal profession’.

In a chapter on research, Michael Rustin argues that the process of knowledge generation in the clinical fields of psychoanalytical and systemic psychotherapy are inadequately captured by conventional concepts of research in psychology and psychiatry. He highlights the valuable convergence taking place between psycho-analytical research and some forms of empirical developmental psychology, which he considers demonstrates the ‘fertility of methodological pluralism in the mental health field’. He points out the discrepancy between ‘pure models’ and their everyday application. The medical profession's emphasis on ‘normalisation’ (in psychiatry by reference to standard diagnostic classification) differs from the psychotherapists' focus on the ‘elaboration of individual meanings’ and the exploration of identity.

Simon Wessely, in contrast, champions the randomised control trial as the conclusive arbiter of treatments that work as opposed to those that should be avoided. He cites the accumulating evidence that psychological debriefing is not an effective treatment for post-traumatic stress disorder as an example of ‘evidence’ that challenges us because it appears to be counterintuitive. He cautions against the tendency to cling unquestioningly to treatments. All effective treatments have the potential to do harm as well as good, so it behoves us to ascertain whether overall the balance is in favour of the latter rather than the former.

The randomised trial is examined from another perspective by Phil Richardson, who explores the limitations of the ‘drug metaphor’ as applied to psychodynamic psychotherapy. Paul Sturdee, in his chapter, questions the evidential status of scientific research. He points out that scientific evidence is not immune to commercial influences and therefore should be interpreted in that context. The nature of meaning in psychotherapy is looked at by Digby Tantum and he specifically focuses on how psychotherapeutic interventions act as organisers of meaning.

There are further chapters on: single-case methodology; hypothesis-testing in cognitive—behavioural therapy and psychoanalytical psychotherapy; audit; cognitive—analytic therapy; and ‘practice-based evidence’ in psychotherapy.

If there is any criticism of this book it is that the range of contributions makes it difficult to integrate the various arguments into a cohesive whole. However, this diversity is an antidote to the often simplistic promotion of the evidence-based model. Well-balanced, the varied perspectives give the book breadth as well as depth. This is a fascinating and rewarding read and can be recommended as an intelligent guide for practitioners of psychological therapies.