Lack of treatment fidelity can be an important source of variation affecting the credibility and utility of outcomes from behavioral intervention research. Development and implementation of a well-designed treatment fidelity plan, especially with research involving underserved populations, requires careful conceptualization of study needs in conjunction with what is feasible in the population. The purpose of this article is to review a fidelity-monitoring plan consistent with the National Institutes of Health Behavior Change Consortium guidelines (e.g., design, training, delivery, receipt, and enactment) for an intervention trial designed to improve physical activity and nutrition among immigrant and refugee families. Description of the fidelity monitoring plan is provided and challenges related to monitoring treatment fidelity in a community-based participatory intervention for immigrant and refugee families are discussed.