The inclusion of youth voices in research relating to their own daily environments, wellbeing, and development is increasingly recognized as essential to ensuring rigor and success in mobilizing community change. Few studies have qualitatively examined youths' experiences and perceptions in participatory roles. This paper presents insights and lessons learned from a capacity-building program designed and delivered as part of a youth participatory research project, Teens Talk Vaping. Teens Talk Vaping took a by-youth-for-youth research approach to co-produce research about teen vaping to inform evidence-based vaping education materials. The capacity-building program was developed to equip seven teens from the Human Environments Analysis Laboratory Youth Advisory Council (four teen girls, three teen boys; Mage = 17.3) with qualitative research skills to contribute as "teen co-researchers" to all phases of the project, from conceptualization through to dissemination. The teen co-researchers were interviewed at four key phases of the program: qualitative research principles and approaches, data collection, data analysis, and overall reflections. Using thematic analysis, findings revealed the positive implications and practical limitations of the capacity-building program, which may support other academics engaging in participatory methodologies with youth and contribute toward the improvement and enrichment of participatory research opportunities for youth.