Because of developmental constraints on the types of assessment that can be used with young children, teachers' judgments of students' skills and abilities are a particularly important source of information in early education. The present study investigates the accuracy of these judgments by examining agreement between Prekindergarten teachers' (n = 66) judgments of children's (n = 122) emerging math and literacy skills made with teacher rating scales and children's performance on a researcher-administered demand performance assessment. Average agreement between measures was 71% for language and literacy items and 66% for math items. When disagreements occurred for language and literacy skills, they were more likely a result of teachers reporting that children had fewer skills than indicated by the demand performance assessment, rather than more. For math, teachers were equally likely to report either fewer or more math skills than indicated by the performance measure. Teachers' over- and underestimations of children's skills were related to their ratings of the children's social-emotional functioning and the type of skills being assessed. Children's gender and race were not related to teacher accuracy; neither were teacher education or years of experience.