Hyperactivity is a potentially confusing concept with different terminology and history in Europe and the U.S.A. There is a certain amount of suspicion among U.K. practitioners as to whether it is appropriate to recognise it as a primary condition. Perhaps because of this, assessment procedures vary between practitioners and centres. Using our experience of running a specialist overactivity and attention disorders clinic (now defunct) at St George's Hospital, London we draw together recommendations for the assessment of this serious clinical problem.