The present study examined child and school factors that might foster classroom behavioral engagement during the first year at school in a sample of 67 typically developing British 4-year-olds. The children were followed for 9 months from the summer before enrollment through the first 7 months of school. Our findings showed that effortful control and attachment security facilitated engagement, whereas impulsivity adversely affected engagement. The children's classroom engagement was further supported by close relationships with the teachers, but those who had more conflicts with the teachers or had developed avoidant feelings toward school tended to be more disengaged in the classroom. This study suggests that features of the child and environment collectively affect the early development of behavioral engagement at school, with some features possibly playing a more significant role at some than other phases during school transition. Limitations, implications, and suggestions for future research are discussed.