This study examined the relationships between implementation of a school-wide approach to behavior, School-wide Positive Behavior Support (SWPBS), and teacher self-efficacy. Twenty-two teachers from schools implementing SWPBS and 40 teachers from schools not implementing SWPBS completed a questionnaire measuring aspects of self-efficacy. Differences in ratings of self-efficacy were examined using multilevel modeling. Results showed that teachers at SWPBS schools reported significantly higher perceptions of teacher self-efficacy when controlling for school-level effects. Results are discussed in terms of implications for future research and practice. (Contains 2 tables.)