Examining implementer fidelity: conceptualising and measuring adherence and competence

The positive outcomes demonstrated in programme efficacy trials and the apparent ineffectiveness of programmes in community settings have prompted investigators and practitioners to examine implementation fidelity. Critically important, but often overlooked, are the implementers who deliver evidence‐based programmes. This article distinguishes fidelity at the programme level from implementer fidelity. Two components of implementer fidelity are defined. It is proposed that implementer adherence and competence are related but unique constructs that can be reliably measured for training, monitoring and outcomes research. Observational measures from a school‐based preventive intervention are used to illustrate the contributions of implementer adherence and competence. Distinguishing implementer adherence to the manual from competence in programme delivery is the next step in child mental health programme implementation research.