Research Findings: Preschoolers' sleep patterns were examined related to cognitive and adaptive functioning. The sample consisted of 874 typically developing preschool children with a mean age of 40.01 months. Parent/caregiver reports of children's sleep pattern factors, Stanford-Binet 5 intelligence scale scores, and Behavior Assessment System for Children, Second Edition, adaptive behavior composite scores were examined. The results provided evidence of the interaction among preschoolers' sleep factors, cognitive variations across performance areas, and adaptive functioning. Practice or Policy: Sleep needs vary according to the child, and maintaining optimal sleep habits will help preschool performance and skills acquisition. Practical implications for prevention, early intervention, education, and policy are discussed.