This study used the standard setting to establish cutscores for the fidelity of implementation of an evidence-based intervention, the Self-Determined Learning Model of Instruction (SDLMI) designed to enhance goal-directed actions in secondary students with and without disabilities. Cutscores were then applied to fidelity data from a large, randomized trial of the SDLMI with teacher implementers. Findings suggest teachers demonstrate a range of fidelity outcomes over time across three dimensions adherence, quality of delivery, and student responsiveness. Almost all teachers (93%) immediately meet cutscores for the adherence dimension after training, but smaller numbers meet cutscores for quality of delivery (64%) and student responsiveness (69%). However, the quality of delivery and student responsiveness showed growth over time with implementation experience and there was a small effect of intensifying implementation support.