This book contains a selection of the proceedings of the Second Meeting of the European Association for Behaviour Therapy and Modification, and of the Fourth Annual Meeting of the Behavioural Engineering Association. The conference, held at Wexford, Ireland, was attended by 320 delegates from most European countries and North America. In the foreword to the proceedings of the previous European Conference Brengelmann and Tunner commented upon the extension of the basis of behaviour therapy. They pointed out that behaviour therapy had developed from the position in the early days, when treatments were derived by almost literal translation of learning principles to the clinic, to the more modern position where therapies were developed from considerations of the results from all experimental disciplines devoted to the study of both human and animal behaviour. Even a superficial consideration of the breadth of the topics repre­ sented in this volume will indicate that this trend has continued.