Purpose: To provide a primer regarding treatment fidelity as it affects evidence-based practice (EBP) for speech-language pathologists. Method: This tutorial defines treatment fidelity, examines the role of treatment fidelity for speech-language pathologists, provides examples of fidelity measurement, and describes approaches for assessing treatment fidelity. Conclusion: Treatment fidelity is a neglected construct in the EBP literature; however, fidelity is a crucial construct for documenting intervention effectiveness and engaging in EBP. (Contains 1 table.)