This study examines the accuracy of parents' reports about their children's sleep behavior and their response to a behavioral treatment. Twenty-eight sleep-disordered and thirty control children aged 12-36 months were filmed during three nights using an infrared camera and their sleep behavior compared with parental reports. There were significant differences among the groups with parents of good sleepers being less accurate in reporting on their children's sleep behavior. Poor sleepers also had more behavior problems, a more difficult temperament and more adverse early medical histories. The good sleepers woke up as frequently as the poor sleepers. However, they managed to soothe themselves back to sleep without disturbing anyone. Virtually all poor sleepers showed significant improvement following treatment.