Chronic sleep disturbance, such as bed refusal, sleep-onset delay, and night waking with crying, affects 15% to 35% of preschool children. Biological factors, particularly arousals associated with recurrent episodes of rapid-eye-movement sleep, render infants vulnerable to repeated awakenings. Parental failure to establish appropriate stimulus control of sleep-related behaviors and parent-mediated contingencies of reinforcement for sleep-incompatible behaviors may shape and maintain infant sleep disturbance. Treatment and prevention strategies are discussed, and research needs are identified.