Self-regulation is a critical component of school readiness and success. Practices for supporting self-regulation may be advanced by a better understanding of factors characterizing children at risk for challenges and contextual mechanisms associated with desirable developmental trajectories. The current study leverages a large national data set and four-level analyses to evaluate an ecological model of self-regulation development that considers student-, classroom-, and school-level factors in relation to teacher-rated self-regulation growth and outcomes across kindergarten and first grade. Analyses identified reliable associations for growth trajectories and the risk factors of being younger, male, and from a low socioeconomic status background; experiencing low student-teacher closeness and high student-teacher conflict; and attending a kindergarten class with lower levels of peer-displayed appropriate behavior. Findings signify the importance of service delivery aimed at advancing the school-based implementation of emotional and organizational supports to promote student-teacher interactions and class-wide demonstration of positive behavior.