The cognitive interview, with a focus on debriefing methods, was developed in the 1980s to identify sources of potential response error in surveys or questionnaires. With the release of the final US FDA guidance, titled 'Patient-Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims', cognitive interviews have gained importance and relevance both for concept elicitation and debriefing purposes in the context of instrument development. This article is intended as a guide for the researcher working with special populations in methods to foster successful cognitive interviews that meet FDA standards. While many of these techniques are broadly applicable, specific recommendations are provided for working with pediatric and cognitively challenged populations, as well as with individuals with communication difficulties.