The No Child Left Behind Act requires that 95% of students in all public elementary and secondary schools are assessed in mathematics. Unfortunately, direct assessments of young students can be timely, costly, and challenging to administer. Therefore, policy makers have looked to indirect forms of assessment, such as teachers' ratings of student skills, as a substitute. However, prekindergarten teachers' ratings of students' mathematical knowledge and skills are only correlated with direct assessments at the .50 level. Little is known about factors that influence accuracy in teacher ratings. In this study, we examine the influence of student and teacher characteristics on prekindergarten teachers' ratings of students' mathematical skills, controlling for direct assessment of these skills. Results indicate that students' race/ethnicity and social competency, as well as teachers' self-efficacy, are significantly related to prekindergarten teachers' ratings of students' mathematical skills. [This article was published in the "Journal of Psychoeducational Assessment" (EJ1144211).]