Research Findings: Behavior regulation, including paying attention, remembering instructions, and controlling action, contributes to children's successful adaptation to and functioning in preschool and school settings. This study examined the development of behavior regulation in early childhood and its potential contribution to individual differences in children's early knowledge (mathematics and vocabulary). Sixty German preschool children were administered a direct observational measure of behavior regulation, the Head-to-Toes Task, and a standardized test to assess early mathematics and vocabulary. Results revealed significant gains in behavior regulation between of 3 and 4 years of age. Moreover, early gender differences were found, with girls outperforming boys at age 4. Behavior regulation was significantly related to performance on the academic tasks, but the pathways to math and vocabulary knowledge differed. Practice or Policy: Discussion focuses on the role of behavior regulation in early academic achievement. (Contains 2 tables and 1 figure.)