Welcome to this special issue of Behavioural and Cognitive Psychotherapy, a Festschrift to mark the retirement of Professor William Yule. The collection of papers here, covering reading problems, parenting and conduct disorder, the effects of war on civilian children, cognitive factors associated with trauma in children, social-cognitive approaches to post traumatic stress, and the assessment of PTSD in children, can only begin to skim the surface of his contribution to clinical child psychology in over 40 years of research, teaching, and – above all – clinical work. It is fitting that such a collection appears in this journal. Bill joined the BABP (later BABCP) as a founder member in 1972. Three years later, he and Ray Hodgson began to co-edit the new quarterly BABP Bulletin, the forerunner to Behavioural and Cognitive Psychotherapy. Bill retired as Editor of the Journal in 1984, having helped to develop what started out as a single sheet newsletter into a successful, respected, international scientific publication. He is also a former Chair of the Association, and was made an Honorary Fellow in 1984.