Numerous evidence-based classroom management strategies to prevent and respond to problem behavior have been identified, but research consistently indicates teachers rarely implement them with sufficient implementation fidelity. The purpose of this study was to evaluate the effectiveness of implementation planning, a strategy involving logistical intervention implementation planning and identification of implementation barriers, and participant modeling, a strategy involving didactic and in vivo intervention training, on teachers' implementation of an evidence-based classroom management plan. A randomized multiple treatment embedded within a multiple baseline design across participants was used to assess (a) teachers' adherence to the classroom management plans and quality of implementation and (b) student disruptive behavior in the classroom immediately and at follow-up. Results indicated that teachers' adherence and quality increased with both implementation planning and participant modeling, but these improvements were not fully maintained at 1- and 2-month follow-up. A similar pattern in student disruptive behavior was also observed. These findings highlight the need for ongoing implementation support for behavioral interventions in schools. Implications for future research and practice are discussed.