Bias resulting from under-reporting has been largely ignored by studies that have examined the relationships between psychosocial factors and unintentional childhood injuries. This study was part of a larger investigation that examined associations between psychosocial factors and unintentional childhood injuries in a sample of 781 children. Visits to an accident and emergency department and their general practitioners were used to determine whether the children or their mothers were under-reporters. "Under-reporters" were compared with "reporters" on a variety of family, behavioural, and development factors. The analyses showed that under-reporters did not differ significantly from the remainder of the sample in terms of psychosocial factors central to the main study.