The scientific approach advocated in CBT has increased its credibility with more biologically orientated therapists (who have remained sceptical of other psychodynamic models), making the approach acceptable to a broad group of psychiatrists. There is a rich clinical literature describing the techniques and applications of CBT in a wide variety of settings. The acquisition of a selection of the above texts offers a useful starting point, and scanning of major British and American psychiatry and psychology journals is likely to turn up at least one important paper every few months. Those with a commitment to research would benefit from subscribing to the journal Cognitive Therapy and Research.

CBT does not aim to be a panacea for every disorder, and cognitive therapists are critical of its overzealous use by inadequately trained or poorly informed therapists. To practise effectively, the therapist needs a coherent cognitive model of the problem being treated and, as such, must explore the theoretical background literature and critically evaluate the data from process and outcome research. Hopefully, this ‘scientist-practitioner’ approach, tracing the emergence and development of the theory and principles of the model underpinning the therapy, means that cognitive therapists practise what they preach.

To summarise then, in 1962 RET displayed important features still current. These include the inter-relatedness of cognitive, emotive and behavioural processes, the important role that cognition plays in psychological problems, its humanistic view of the self, and the futility and dangers of self-rating. The emphasis on perpetuation rather than acquisition processes of emotional disturbance holds good now as it did then, and the core view of therapeutic change is essentially the same now as it was in 1962, despite further, more recent elaborations.

Significant change has occurred in RET since 1962 that updates several of Ellis' original ideas. These include the distinction between interpretations (or inferences) and evaluations, the primary of musts in accounting for psychological disturbance, the clear distinction between healthy and unhealthy negative emotions and the greater role according to force and energy in the change process. In addition, a greater emphasis is placed on biological aspects of emotional disturbance now than 30 years ago. Finally, a greater range of cognitive, imaginal, emotive and behavioural methods are found in current RET literature than in Reason and Emotion in Psychotherapy, where Ellis restricts himself to illustrating a few cognitive and behavioural techniques.

RET, then, has grown and developed over the past 30 years. In large part, this reflects the theory's flexibility and the competent people who have worked to make RET one of the most viable and widely used cognitive-behaviour therapies.