Disadvantaged groups bear a disproportionate burden of disease (called ‘health inequity’), with one of the crucial mechanisms being a higher exposure to health risk factors, such as smoking. Adolescents from deprived population groups experience a higher exposure to smoke, which not only affects their health at a young age, but also lowers the threshold of becoming smokers themselves, pertaining to health inequity also at a later age. Health promotion interventions may help to prevent these adverse outcomes. The school is often used as a setting to implement such interventions, as the majority of adolescents (including disadvantaged groups) can be easily accessed through schools. However, it has been shown that school-based interventions are less effective among disadvantaged youth, suggesting another approach is needed. There is an exponential growth worldwide in the use of sport and recreation (SR) settings for public health purposes. This promising line of research contends that positive outcomes of SR settings, including health and well being, are achieved as a result of an increased sense of community that is built among participating youth, and with youth coaches. SR settings may therefore provide a potential mean for delivering smoking prevention messages, but how and under which conditions is still to be investigated. Consequently, the purpose of this project is to gain understanding on the association between SR activities and smoking, and develop and evaluate an intervention in an SR setting that aims to reduce smoking initiation in disadvantaged youth aged 12 to 18 years. A multi-method approach is used. In a first phase, realist methodology will be used as a framework for synthesising evidence regarding what in public smoke interventions does work (or not) in SR settings for disadvantaged youth, and under which circumstances. To this aim, a rapid literature review and qualitative study methods will be applied and will lead to the development of a working theory on how to approach and engage disadvantaged youths using SR as a lever. A second phase involves the development and evaluation of the non-smoking intervention. To achieve this, a participatory-based Intervention Mapping (IM) approach will be used. The intervention will be carried out and implemented throughout several consecutive steps from stating intervention goals and defining behavioural change techniques to program components, pre-testing and implementation. A participatory design with relevant stakeholders (including youth and youth coaches) will be used to synthesize all knowledge and expertise by mapping, integrating and revising the co-creation of the final intervention. To evaluate the intervention, a cluster randomized controlled study will be used in which SR settings throughout Flanders will be randomly allocated to either the intervention group or the control group (practice as usual). The project will provide novel insight into how approaching and engaging hard-to-reach youth in smoking prevention actions. If the intervention has proven to be effective, a ready-to-use intervention package will be compiled and disseminated to settings working with disadvantaged groups.