Background Implementing evidence-based programs in community service settings introduces the challenge of ensuring sustained fidelity to the original program. We employ a fidelity measure based on direct observation of practitioners' competence and adherence to the evidence-based parenting program (EBPP) GenerationPMTO following installation in national and international sites. Fidelity monitoring is crucial, especially when the program purveyor transfers administration of the program to the community as was done in this case. In previous studies, the Fidelity of Implementation rating system (FIMP) was used to evaluate practitioners' fidelity to the GenerationPMTO intervention in six countries following implementation showing high levels of adherence up to 17 years post certification. Other studies showed FIMP to have predictive validity. The present study provides inter-rater reliability data for this fidelity tool across teams of the purveyor, Implementation Sciences International, Inc./ISII, and national and international sites over a five-year period. Methods Data assess inter-rater reliability in terms of percent agreement and intraclass correlation (ICC) for the purveyor's two fidelity teams and the fidelity teams in seven implementation sites. Results Results report stable good to excellent levels of inter-rater reliability and ICCs as well as good attendance at fidelity meetings for all fidelity teams. Conclusions This observational method of assessing fidelity post implementation is a promising approach to enable EBPPs to be transferred safely from purveyors to communities while maintaining reliabile fidelity to the intervention.