This revised edition is being offered given an evident need to update, expand, and clarify aspects of the first edition which appeared now almost two decades ago, and given a keen wish by Tony Ryle to do this. Our aim was to offer a summary but comprehensive overview of the current evolved Cognitive Analytic Therapy (CAT) model, its background and comparative context, and of its range of applications, that would be informative and helpful to those new to the model, to trainees and even established practitioners. Very sadly however, as many readers will be aware, not long after being commissioned to do this Tony, who was the senior author and progenitor of the cognitive analytic therapy model, developed a serious illness from which he ultimately succumbed in 2016. Summaries of his remarkable creative personality, his career and contributions to the field of psychotherapy and mental health more broadly have been published in various obituaries which are available on the internet and in a special issue published in 2018 of Reformulation the newsmagazine of the Association for Cognitive Analytic Therapy (ACAT) in the UK, also available on-line.