The “Person-based Approach” to intervention development uses qualitative and mixed methods to ensure that the process of intervention development takes into account the beliefs, attitudes, needs and context of the particular user group the intervention is designed to target. Qualitative research is used in several ways: in the form of a background literature search, in collecting qualitative data from target users to assess their specific needs, and in “think-aloud” interviews that gather detailed feedback on each aspect of the intervention from target users. This allows iterative development of the intervention to be based directly on the input of the target users. We provide an overview of best practices when using the Person-based Approach, together with examples of aspects of intervention development from previously-developed interventions. Including feedback from target users from the beginning of intervention development results in interventions that are more likely to make a difference in practice