Although it is common for researchers to assess implementation fidelity (IF) within the context of math intervention, IF assessments are often restricted to intervention adherence. Further, the degree to which IF influences observed outcomes is commonly ignored. The current study examined the relationship between three aspects of IF and the math performance of 1,340 grade 4 through 8 students who participated in an evidence-based math intervention. A series of multilevel regression models were fit to the data, including a final model with an indicator of intervention adherence, intervention delivery quality, and intervention engagement. A significant and positive association was observed between students' math performance and intervention engagement; however, a similar relationship was not observed when examining the impact of adherence and the quality of intervention delivery on students' math performance. Results are discussed in the context of implementation research for educational interventions.