Fidelity is determining if a program or practice is being delivered as intended. Fidelity assessment and monitoring helps to identify the degree to which core intervention components are in place during the delivery process. Five dimensions of intervention fidelity, as originally articulated by Dane and Schneider (1998) and later reinforced by Mihalic (2004), have frequently been utilized within implementation science: (1) adherence, (2) exposure, (3) quality, (4) participant responsiveness, and (5) program differentiation.

Dane, A. V., & Schneider, B. H. (1998). Program integrity in primary and early secondary prevention: are implementation effects out of control? Clinical psychology review, 18(1), 23–45. https://doi.org/10.1016/s0272-7358(97)00043-3

Mihalic,  S. (2004). The importance of implementation fidelity. Emotional and Behavioral Disorders in Youth, 4(4), 83–105. https://www.incredibleyears.com/wp-content/uploads/fidelity-importance.pdf