There is a growing recognition of the value of measuring fidelity of implementation (FOI) as a necessary part of evaluating interventions. However, evaluators do not have a shared conceptual understanding of what FOI is and how to measure it. Thus, the creation of FOI measures is typically a secondary focus and based on specific contexts and programs. This article describes a project that holds the development of FOI measures as its primary goal and has developed a suite of data collection tools designed to be used across multiple programs. It describes the foundation of the suite--a conceptual framework for clearly and specifically describing FOI and the need for the framework. It also describes where the framework resides in existing literature and how it can be used to support measurement of interventions in education and other fields. (Contains 4 tables and 4 notes.)