Research emphasizes the importance of fidelity assessment in the delivery of evidence-based interventions for autistic children, but it is underutilized in community settings. There is a need for effective tools supporting provider training and fidelity measurement within usual care autism services. The purpose of this study was to examine the feasibility, acceptability, and impact of a supervisor training suite to support community-based provider use of a naturalistic behavioral intervention, Pivotal Response Training (PRT). This study applied a nonconcurrent multiple baseline design to evaluate the feasibility, acceptability, and impact of a supervisor toolkit including a PRT intervention fidelity assessment tool and accompanying package of coaching, feedback, and implementation strategies for supporting provider training. Supervisors (n = 5), providers (n = 17), and autistic children (n = 17) participated in the study. Results indicate high levels of adherence to and satisfaction with the Toolkit. Supervisor training in the Toolkit was effective for supporting most providers in successfully using more difficult PRT components and had varied impact on provider implementation of PRT overall. This study contributes to the literature on effective professional development strategies for training providers in evidence-based naturalistic behavioral interventions. The integration of training in the use of a fidelity tool, with planning, coaching, and implementation strategies to support the process, may improve training quality and warrants further research.