To explore whether parental report of frequency of problematic sleep behaviours overestimates the subjective experience of sleep problems among co-sleepers, and whether classification as reactive or intentional co-sleeping is related to parental judgments about children's sleep, 139 parents of young children were recruited from urban paediatric offices. The Child Sleep Behaviour Survey asked about potentially problematic sleep behaviours, and yielded a simple frequency score (frequency of all items) and a weighted frequency score (only behaviours considered problematic by the parent). Parents described sleeping arrangements and demographic characteristics. Simple frequency of behaviours was higher among co-sleepers than among solitary sleepers. Weighted frequencies were lower in all groups, but highest among reactive co-sleepers. Parents of intentional co-sleepers notice children's sleep behaviours that they do not consider problematic. Copyright © 2007 John Wiley & Sons, Ltd.