Increasingly, states establish different thresholds on the Early Childhood Environment Rating Scale-Revised (ECERS-R), and use these thresholds to inform high-stakes decisions. However, the validity of the ECERS-R for these purposes is not well established. The objective of this study is to identify thresholds on the ECERS-R that are associated with preschool-aged children's social and cognitive development. Applying non-parametric modeling to the nationally-representative Early Childhood Longitudinal Study Birth Cohort (ECLS-B) dataset, we found that once classrooms achieved a score of 3.4 on the overall ECERS-R composite score, there was a leveling-off effect, such that no additional improvements to children's social, cognitive, or language outcomes were observed. Additional analyses found that ECERS-R subscales that focused on teaching and caregiving processes, as opposed to the physical environment, did not show leveling-off effects. The findings suggest that the usefulness of the ECERS-R for discerning associations with children's outcome may be limited to certain score ranges or subscales.