The transition to school is seen as an extensive process of adaptation during which children need to adjust to school standards. Successful adaptation is reflected in children’s classroom behavior and academic performance. In the current study, it was considered to be important to control for the influence of other child characteristics and mother’s level of education, which are presumed to be related to academic performance. The present study aims to test the relationship between behavior regulation in kindergarten and adaptation to school in first grade. This study aimed to examine the influence of kindergarten children’s behavior regulation on their adjustment to school, focusing on both academic and social outcome indicators. This study has important methodological strengths. Children’s behavior regulation was measured by two different observational situations. Outcome indicators for school success included both teacher evaluations and standardized performance tests.