From the abstract: "Prior research indicates that preschool classroom quality is positively associated with children’s emergent academic skills at the end of the preschool period, but these associations appear to diminish during kindergarten (K). To consider the accumulation of classroom experiences during preschool and K, data were drawn from a sample of children (N?=?1015) who participated in state-funded pre-K programs across six states and were followed into the spring of K. We examined if pre-K and K classroom quality were associated with children’s language, literacy, and mathematics skills in the spring of K after controlling for pre-K entry skills, child background demographics, and other classroom covariates. Classroom quality was assessed with the Classroom Assessment Scoring System. We found that additive cumulative effects described associations between classroom quality and children’s language and literacy outcomes. For language skills, higher-quality pre-K Instructional Support predicted better K language skills at all levels of Instructional Support quality in K, but higher-quality K Instructional Support also contributed to the prediction of better K language skills in an additive manner. For literacy skills, higher-quality pre-K Instructional Support, Emotional Support, and Classroom Management predicted better K literacy skills at all levels of K quality, but each domain of K quality also contributed to the prediction of better K literacy skills in an additive manner. In contrast, for mathematics, we found that multiplicative cumulative effects described associations between classroom quality and K mathematics skills such that the positive predictive effect of pre-K Instructional Support and Emotional Support was enhanced as the level of K quality increased in each of these domains, respectively. Moreover, sensitivity analyses revealed that higher-quality pre-K Instructional Support and Emotional Support significantly predicted better K mathematics skills for children who experienced high, but not average or low levels of K quality in these domains, respectively. Implications are discussed in relation to classroom quality alignment during pre-K and the early elementary grades."