In intervention research, treatment fidelity is defined as the strategies that monitor and enhance the accuracy and consistency of an intervention to ensure it is implemented as planned and that each component is delivered in a comparable manner to all study participants over time. Reviews of the literature in special education and other disciplines reveal that reports of treatment fidelity are limited. In this article, we examine some recommendations made by the National Institutes of Health Behavior Change Consortium that may be adapted to document treatment fidelity in educational research. We discuss the critical importance of planning for, collecting, and reporting treatment fidelity data at each stage of intervention research and discuss the implications of these practices for validity issues, efficacy and effectiveness studies, and cost-benefit considerations. Throughout the article, we use our own classroom-based research to provide examples of expanding treatment fidelity in randomized field trials.