Abstract
<p>Youth engagement is increasingly recognized as an important strategy for strengthening health promotion interventions, yet few studies provide detailed methodological accounts of how youth co-design can be implemented in practice. This paper describes the development and implementation of the E-Prevention And Vaping (EPAV) youth co-design methodology and examines how this participatory model functioned in practice. EPAV used a structured multi-stage co-design process that integrated youth co-researchers within the research team and engaged youth aged 15 to 24 in participatory workshops to develop vaping prevention messaging. An embedded convergent mixed methods process evaluation assessed participants’ experiences of the co-design process using post-workshop surveys that included closed and open-ended questions. Findings indicated high levels of satisfaction, perceived inclusion, and workshop effectiveness, as well as the importance of interactive activities, collaborative dialogue, and cultural grounding. These findings demonstrate how structured youth co-design approaches can support meaningful engagement while generating concrete intervention outputs for youth-focused health promotion initiatives.</p>