Despite evidence that high-quality preschool programs have substantial, long-lasting impacts on young children's developmental outcomes, associations between preschool quality measures and children's cognitive outcomes within preschool programs are generally small or null. Using data from a large urban prekindergarten program, we examined associations between children's receptive vocabulary and executive function skills and several indicators of classroom quality. Ours is the first such study within a program that has been shown to have small-to-large causal impacts on children's language, literacy, mathematics, executive function, and emotional development outcomes. Consistent with prior literature, we found small or null associations between quality predictors and children's outcomes and we found that some of these relationships were curvilinear. Findings are discussed in light of several hypotheses in the literature regarding the general pattern of small or null associations, including the psychometrics of commonly used quality measures and possible range restriction of quality indicators. (Contains 1 figure and 5 tables.)