This paper focuses on the international experience with early identification and intervention for children with AD/HD. Much less is known about AD/HD in two- to five-year-old preschool children than is known for older school-aged youngsters. Despite this lack of knowledge, AD/HD is increasingly recognized in this population and stimulant medication increasingly prescribed to treat it. The lack of control of temperamental patterns in preschoolers seems related to later observations of hyperactivity, attention problems and antisocial behaviours in school-aged children. The emergence and continuity of AD/HD-like behaviours is influenced not only by genetic, pre- and perinatal factors, but also by social context factors. All these influences interact with a child's developmental needs in complex ways according to a systemic bio-psychosocial model. The undiagnosed AD/HD child will often be labelled by parents as difficult and the family scapegoat. Because of the age of the children and the variety of 'normal behaviour' in this group, interventions should include systemic, environmental and play-centred approaches.