Although evidence-based practices for students' social, emotional, and behavioral health are readily available, their adoption and quality implementation in schools are of increasing concern. Teachers are vital to implementation; yet, there is limited research on teachers' openness to adopting new practices, which may be essential to successful program adoption and implementation. The current study explored how perceptions of principal support, teacher affiliation, teacher efficacy, and burnout relate to teachers' openness to new practices. Data came from 2133 teachers across 51 high schools. Structural equation modeling assessed how organizational climate (i.e., principal support and teacher affiliation) related to teachers' openness directly and indirectly via teacher resources (i.e., efficacy and burnout). Teachers with more favorable perceptions of both principal support and teacher affiliation reported greater efficacy, and, in turn, more openness; however, burnout was not significantly associated with openness. Post hoc analyses indicated that among teachers with high levels of burnout, only principal support related to greater efficacy, and in turn, higher openness. Implications for promoting teachers' openness to new program adoption are discussed.