Michael Barkham is Professor of Clinical Psychology and Director of the Centre for Psychological Services Research at the University of Sheffield. He has published approximately 150 scientific papers and 30 book chapters in the fields of clinical psychology, counselling, and psychotherapy and has an abiding commitment to strengthening the paradigm of practice-based evidence. Gillian E. Hardy is Professor of Clinical Psychology and Director of the Clinical Psychology Unit and the Doctorate in Clinical Psychology training programme at the University of Sheffield. She has published extensively in the field of psychotherapy outcome and process research. John Mellor-Clark has been engaged in the evaluation of UK psychological therapies and counselling for the past 20 years. Through the mid-1990s, he led the development of the CORE System as the first standardised quality evaluation system in the UK for psychological therapy. Today this system is used by over 250 services and 3, 500 clinicians to help measure, monitor, and manage therapy outcomes.