Objectives. To identify an evidence-based intervention to promote changes in diet and physical activity and adapt it for a UK primary care setting for people with high cardiovascular risk. Design. A three-stage mixed-methods design was used to facilitate a strategic approach to programme selection and adaptation. Method. Stage 1: Criteria for scientific quality and local appropriateness were developed for the selection/adaptation of an intervention to promote lifestyle change in people of high cardiovascular risk through (1) patient interviews, (2) a literature search to extract evidence-based criteria for behavioural interventions, and (3) stakeholder consultation. Stage 2: Potential interventions for adaptation were identified and ranked according to their performance against the criteria developed in Stage 1. Stage 3: Intervention mapping (IM) techniques were used to (1) specify the behavioural objectives that participants would need to reach in order to attain programme outcomes, and (2) adapt the selected intervention to ensure that evidence-based strategies to target all identified behavioural objectives were included. Results. Four of 23 potential interventions identified met the 11 essential criteria agreed by a multi-disciplinary stakeholder committee. Of these, the Greater Green Triangle programme (Laatikainen et al., 2007) was ranked highest and selected for adaptation. The IM process identified 13 additional behaviour change strategies that were used to adapt the intervention for the local context. Conclusions. IM provided a useful set of techniques for the systematic adaptation of an existing lifestyle intervention to a new population and context, and facilitated transparent working processes for a multi-disciplinary team.