Null relations between CLASS scores and gains in children’s language, math, and executive function skills: A replication and extension study

•CLASS scores are not associated with children’s gains in vocabulary and executive function skills across linear and non-linear models.•CLASS scores are not associated with children’s gains in math skills across linear and non-linear models.•Child baseline skills did not moderate the relations between CLASS scores and child gains in prekindergarten.•More measurement work is needed to understand classroom processes driving children’s gains in prekindergarten. General measures of process quality are widely used in the early childhood education (ECE) field. However, the evidence regarding associations between the most widely used process quality measure, the Classroom Assessment Scoring System (CLASS; Pianta et al., 2008), and children’s school readiness gains during the preschool year is mixed. Using data collected during the 2016–2017 school year, we replicate prior work from the 2009–2010 school year which analyzed associations between CLASS scores and children’s gains in language and executive function during the year when children were enrolled in a high-quality public prekindergarten program (Weiland et al., 2013). Additionally, we extend prior work by examining gains in numeracy skills and heterogeneous associations by children’s skills at preschool entry. Participants were teachers in 42 preschool classrooms and a random sample of 307 children. Across linear, quadratic, and spline models, we found that none of the CLASS domains were associated with children’s gains in vocabulary and executive function skills. We found no evidence of moderation by child baseline skills. We discuss future directions for measuring and analyzing process quality in prekindergarten.