In his book, Alan Carr gathers together and summarises a large body of evidence. Covering a comprehensive range of presentations across the age spectrum and wading through a huge number of systematic reviews and meta-analyses must have required great stamina. Carr starts by explaining the background to and methods used in psychotherapy research. He then covers research examining factors influencing outcome that are common to all psychotherapies (such as quality of therapeutic relationship), before undertaking an extensive review of the outcome literature diagnosis by diagnosis for psychotherapy with children, adolescents, adults and older people. The book is written in an accessible, easy to understand style, with a helpful summary at the end of each section. However, what the book has achieved in abundance in breadth, it lacks equally in depth.

What more in-depth examinations of the psychotherapy literature have found is that the ‘contextual’ (or common factors) model explains the research findings much better than the ‘medical model’ (or diagnosis-specific techniques). All recognised formal psychotherapies are effective to roughly the same degree for all common mental health problems; factors such as quality of therapeutic alliance have a much more significant impact on outcome than matching diagnosis to technique. Whenever there is a fair, properly conducted, head-to-head comparison (i.e. similar duration of treatment using the same number of sessions with properly trained therapists who are supportive of the model of intervention they are using), the results are that each model is equally effective, and client/therapist variables, particularly therapeutic relationship, have a far greater impact on outcome than technique. There was nothing in this book that contradicted this repeated finding. Although Carr refers to these ‘common factor’ findings early on, he then loses his way by dividing the evidence by diagnostic categories, thus giving a misleading impression that for specific diagnoses there are specific techniques to be used that trump others. My knowledge of some of the studies and reviews he discusses also led me to conclude that Carr lacks a more critical questioning and perhaps accepted some abstracts at face value, leading in places to incorrect conclusions. Thus, I think a better and more analytically thorough job is done by some of the older texts such as Bruce Wampold's The Great Psychotherapy Debate (2001).