Contextualizing the role of teachers in social-emotional learning (SEL) in Malawi, we examine how teachers' "comfort" with, "commitment" to, and perceived school "culture" toward SEL relate to their actual teaching of it. Using surveys from 432 primary school teachers (20-60 years old), we found teacher "comfort" and supportive school "culture" were positively related to integration of SEL into classroom instruction, while "commitment" had no statistically significant relationship with implementation. We explore plausible explanations for these findings by interviewing 42 teachers. Together, our findings highlight the importance of teacher support systems and cultural compatibility of the curriculum for successful SEL implementation.