Research Findings: The current study investigated the predictive utility of teacher-rated, observed, and directly assessed behavioral self-regulation skills to academic achievement in preschoolers. Specifically, this study compared how a teacher report (the Child Behavior Rating Scale), an observer report (the Observed Child Engagement Scale), and a direct assessment (the Head-Toes-Knees-Shoulders task) relate to early math and literacy skills. The sample consisted of 247 children from 31 preschool classrooms. Trained research assistants observed a subsample of 104 children. Results indicated significant positive relationships for teacher-rated and directly assessed behavioral self-regulation for early math and literacy skills. Teacher ratings were the strongest predictors of literacy, and the direct assessment emerged as the strongest predictor of math. Observed behavioral self-regulation was not significantly related to either academic domain. Practice or Policy: Discussion focuses on the domain specificity of behavioral self-regulation assessments and the importance of utilizing multiple measurement tools when assessing behavioral self-regulation and its relations to early achievement.