School professionals who work with students with autism spectrum disorder (ASD) play a significant role in the academic experiences of these students, but some evidence suggests that teachers of students with ASD experience a high risk of burnout. Research has begun to examine factors that ameliorate or prevent teacher burnout, including teacher training and teacher self-efficacy, or teachers' beliefs regarding their abilities to bring about positive outcomes for their students. The present study examined variables associated with the self-efficacy of school professionals for working with students with ASD, including knowledge about ASD, prior experience working with students with ASD, and prior training in ASD and evidence-based practices. A second goal of the present study was to investigate the impact of training on ASD and evidence-based practices on school professionals' knowledge and self-efficacy related to working with students with ASD. In particular, the participants received training on the Prevent-Teach-Reinforce model. Results of the present study suggested the importance of training to school professionals' self-efficacy, highlighting the need for continued efforts to provide quality training to individuals who work with students with ASD.