Substance Abuse & Mental Health Services Administration

The Substance Abuse and Mental Health Services Administration (SAMHSA)

Balancing Fidelity and Adaptation

Fidelity refers to the degree to which a program is implemented as its developer intended. The higher the fidelity, the greater the likelihood that its impact will be similar to that found in the settings where the program was first implemented or tested. Oftentimes, however, programs have to be adapted to the cultural, historical, or other contexts of a particular setting. As the Institute of Medicine explains, “a community identifies an evidence-based program that matches its needs, values, and resources and modifies or adopts elements of the program to maximize community acceptance, implementation, and sustainability.”

For example, when baking a cake, you have to be faithful to the recipe or it may not work out at all—changing the flavor of the icing might be okay, but changing the amount of flour or salt could be disastrous! The same applies to prevention: it is possible that some elements of an intervention could be adapted without adversely influencing the outcome, but most elements must be kept the same. It is sometimes necessary, however, to adapt an intervention to fit certain population groups, budget constraints, staff availability, time limitations, or other issues. In these situations, finding the right approach that will both stay faithful to the original evidence-based design but that will also address the unique characteristics of a community means carefully balancing fidelity and adaptation.

Here are some general guidelines to follow when adapting a program:

  • Select programs with the best practical fit to local needs and conditions. This will reduce the likelihood that you will need to make any significant adaptations.
  • Select programs with the largest effect size. In general, a program with a large effect size is less likely than a similar program with a small effect size to have the relevant outcome reduced by an adaptation.
  • Change capacity before changing the program. It may be easier to change the program, but changing local capacity to deliver it as it was designed is a safer choice.
  • Consult with the program developer. Consult with the program developer to determine what experience and/or advice he or she has about adapting the program to a particular setting or circumstance.
  • Retain core components. There is a greater likelihood of effectiveness when a program retains the core component(s) of the original intervention
  • Be consistent with evidence-based principles. There is a greater likelihood of success if an adaptation does not violate an established evidence-based prevention principle.
  • Add, rather than subtract. It is safer to add to a program than to modify or subtract from it.



  • Backer, T.E. (2002). Finding the balance: Program fidelity and adaptation in substance abuse prevention: A state-of-the-art review. Rockville, MD: Substance Abuse and Mental Health Services Administration (SAMHSA), Center for Substance Abuse Prevention (CSAP).
  • Brounstein, P., Zweig, J., & Gardner, S. (1998). Science-based practices in substance abuse prevention: A guide. Rockville, MD: SAMHSA, CSAP.
  • Brounstein, P. (2003). The continuing adventures of fidelity and adaptation [satellite broadcast]. Presented at Implementing Science-based Prevention Programs Effectively: A Forum on Fidelity and Adaptation sponsored by the Northeast CAPT, Knoxville, TN.
  • O’Connell, M. E., Boat, T., & Warner, K. E. (Eds.). (2009). Preventing mental, emotional, and behavioral disorders among young people: Progress and possibilities. National Research Council and Institute of Medicine of the National Academies. Washington, D.C.: The National Academies Press.