Community sport has emerged in the past decades and uses sports as a lever to improve health and well-being among socially disadvantaged youth. Despite this premise, we do not know whether and to what extent health promotion aims are achieved within community sports practice. Measurable actions are needed, but it can be hard for researchers or practitioners to know how to approach this. This study aimed at developing a health-promoting intervention targeting youth attending community sports. To this aim, we used a planned approach for intervention design within a community-based participatory research design. The result is a group-based program promoting health-supportive behavior among community sport coaches, as we found coaches to be quintessential in fostering motivation toward health behavior change in vulnerable youth attending community sports. The design of such a complex intervention is difficult, yet tractable, when using a planned approach. Of importance, community engagement was the core of our work and we provide the reader with detailed examples on the combined use of participatory research and planned intervention design. This article provides an exemplar of how to approach the development of a health-promoting intervention in hard-to-reach populations.