Teachers play a critical role in establishing classroom and school environments that contribute to students' social and emotional development. This paper explores whether we can estimate a classroom-level measure of student growth in SEL by applying value-added models to students' [social-emotional learning] SEL. We analyze data from the 2016 and 2017 administrations of student self-report surveys, which contain responses from roughly 40,000 students in Grade 5 within five of California's CORE Districts. We estimate separate value-added models for each of the four SEL constructs assessed--growth mindset, self-efficacy, self-management, and social awareness--and for math and [English language arts] ELA academic growth. We find across-classroom-within-school variance of students' SEL outcomes, even after accounting for school-level variance. The magnitude of classroom-level impacts on students' growth in SEL appears similar to impacts on students' growth in ELA and math, although the growth models of SEL do not perform as well as growth models of academic outcomes. Results suggest that across-classroom-within-school impacts may be larger in magnitude than across-school impacts on students' SEL growth. Finally, we show that there are generally low correlations between classroom-level growth in SEL and classroom-level growth in ELA or math; however, growth mindset stands apart from the other three SEL constructs in that there is a moderately strong relationship. By assessing whether we can develop a sound approach for measuring classroom-level impacts on students' SEL, we aim to contribute to the growing body of knowledge about appropriate and innovative uses of data on students' non-cognitive and social-emotional learning. [For the policy brief, "Can We Measure Classroom Supports for Social-Emotional Learning?," see ED600449.]