This study examines the influence of ASD-specific training or professional development, peer observations, feedback from consultation/collaboration and teacher attitudes on general education teacher’s self-efficacy beliefs for educating students with ASD, as well as whether knowledge mediates the effect of professional development on teacher self-efficacy. It is hypothesized that the proposed theoretical model of teacher self-efficacy for educating students with ASD will fit an empirical model based on collected data. Data from 536 participants have been collected and are being analyzed. Preliminary results suggest that the hypothesized model does not fit the empirical model. However, the factors appearing to have the most influence on teacher self-efficacy are knowledge of ASD and teacher attitudes.