A number of classroom-based interventions have been developed to improve social and behavioral outcomes, yet few studies have examined how these programs impact the teachers who are implementing them. Impacts on teachers may affect students, and therefore also serve as an important proximal outcome to examine. The current study draws upon data from a school-based randomized controlled trial testing the impact of two prevention programs. In one intervention condition, teachers were trained in the classroom behavior management program, PAX Good Behavior Game (PAX GBG). In a second intervention condition, teachers were trained to use an integrated program, referred to as PATHS to PAX, of the PAX GBG and a social and emotional learning curriculum called Promoting Alternative Thinking Strategies (PATHS). This study aimed to determine whether both interventions positively impacted teachers, with a particular interest in the teachers' own beliefs and perceptions regarding self-efficacy, burnout, and social-emotional competence. The sample included 350 K-5 teachers across 27 schools (18 schools randomized to intervention, 9 to control). Multilevel latent growth curve analyses indicated that the PATHS to PAX condition generally demonstrated the most benefits to teachers, relative to both the control and PAX GBG conditions. These findings suggest that school-based preventive interventions can have a positive impact on teachers' beliefs and perceptions, particularly when the program includes a social-emotional component. Several possible mechanisms might account for the added benefit to teachers. Additional research is needed to better understand the mechanism by which these programs impact teachers, as well as students. [This paper was published in "Prevention Science" v17 n3 p325-337 2016.]