Measures of school-level growth in student outcomes are common tools used to assess the impacts of schools. The vast majority of these measures are based on standardized tests, even though emerging evidence demonstrates the importance of social-emotional skills (SEL). This paper uses the first large-scale panel surveys of students on SEL to produce and evaluate school-level value-added measures by grade for growth mindset, self-efficacy, self-management, and social awareness. We find substantive differences across schools in SEL growth, of magnitudes similar to those for academic achievement. This result suggests that schools might contribute to students' SEL. However, we also find that the models are not as well specified for SEL as they are for achievement gains, raising the possibility that the estimated school effects include school-level measurement error and potential omitted variables bias. In addition, the across-school variance in the average level of the SEL measures is proportionally much smaller than for academic measures, which would not be expected if substantial impacts of schools on SEL outcomes persisted over time. These findings recommend caution in interpreting measures as the causal impacts of schools on SEL, though they also do not rule out important school effects.