This special edition of Behavioural and Cognitive Psychotherapy is dedicated as a tribute to Isaac Marks, who retires this year from his post as Professor of Experimental Psychopathology at the Institute of Psychiatry, London. All the contributors to this edition are colleagues who have been greatly influenced by Isaac during their careers. Their papers were written without Isaac knowing of our plans and we were even cheeky enough to ask Isaac to write a paper himself, reflecting on his 40 years involvement in the development of behavioural and cognitive psychotherapies. All the papers, including the one by Isaac himself, illustrate some of the areas where he has made a major contribution to behavioural and cognitive psychotherapies during the last 40 years.

Two papers, by Hand and by Rowa, Antony and Swinson, detail the huge advances made in the treatment of the severe and disabling disorders of agoraphobia and OCD, identifying Isaac's enormous contribution. The papers also confirm the international scope of Isaac's influence. These authors remind us not to forget the relative modernity of effective psychological treatments for these disorders and how dramatic a change there has been in prognosis and clinical outcomes.