RAND researchers present results from a spring 2019 survey of a nationally representative sample of kindergarten through grade 12 (K-12) public school teachers about their approaches to supporting students' social and emotional learning (SEL) and the factors that might influence those approaches. The authors explore teachers' SEL practices, including both classroom- and school-level approaches. The authors also examine teachers' beliefs about SEL, their emotional well-being, professional development related to SEL, school-level supports for SEL, and district and state SEL standards. All of these conditions can contribute to the likelihood that educators will adopt high-quality SEL practices. The findings shed light on how SEL practices and supports can depend on the population of students that a school serves and explore how multiple aspects of teacher well-being are related to SEL practices. Although these data were gathered before schools closed because of the coronavirus disease 2019 (COVID-19) pandemic in spring 2020, the findings will continue to be relevant as educators work to enact SEL practices in both in-person and remote instructional contexts in future school years. [For the research brief, "Supports for Social and Emotional Learning in Schools: Findings from the American Teacher Panel. Research Brief. RB-A397-1," see ED609431.]