Performance feedback (PF) is an empirically supported method of increasing teachers' treatment adherence. In the evaluations of PF to date, however, PF was delivered by someone external to the school. The primary purpose of this case study was to provide an exploratory evaluation of the effectiveness and feasibility of PF when delivered by a school-based consultant to teachers implementing a classwide behavioral intervention. Teacher treatment adherence and student outcomes were also evaluated. Results indicate that overall, (a) teachers demonstrated moderate-to-high, but variable, levels of treatment adherence; (b) when teachers demonstrated lower levels of treatment adherence, the school-based consultant implemented PF with high adherence for 5 weeks, after which adherence varied; and (c) student outcomes improved.