OBJECTIVE: This paper presents the results of a realist evaluation of a knowledge translation (KT) intervention implemented in the field of health promotion and disease prevention at the local level in France. DESIGN: Realist evaluation study. SETTING: The target population comprised decision-makers and field professionals working in prevention and public health services operating in regions of France (ie, ARS (Agence Régionale de Santé: regional health agency), IREPS (Instance Régionale d'Education et de Promotion de la Santé pour tous: regional organisation for health promotion and education) and their partners). PARTICIPANTS: This evaluation was based on data collected from 2 seminars, 82 interviews, 18 observations and 4 focus groups over 18 months. INTERVENTION: The TC-REG intervention aimed to increase the use of evidence in cancer prevention, health promotion and disease prevention across four geographical regions in France. The intervention combined various activities: Supporting access to and adaptation of usable evidence, strengthening professionals' skills in analysing, adopting and using policy briefs, and facilitating the use of evidence in organisations and processes. RESULTS: The collected data was used to define favourable/unfavourable contexts for the use of scientific data and mechanisms to be activated to encourage the use of scientific knowledge. From these raw results eight final refined middle-range theories were defined. Organised around the mechanisms to be activated, these middle-range theories illustrate how to activate knowledge and under what conditions. These analyses provided a basis for the production of seven operational and contextualised recommendations to develop KT to inform regional policymaking regarding health promotion and disease prevention. CONCLUSION: The results obtained from the analyses led us to formulate two perspectives of an operational nature for the benefit of those involved in prevention and health promotion.Read less <