Addictive behaviors with detrimental outcomes can quickly become embedded in daily life. It therefore remains a priority to prevent or modify these health behaviors early in the life course. Diffusion theory suggests that community norms are shaped by credible and influential “opinion leaders” who may be characterized by their values and traits, competence or expertise, and social position. With respect to health behaviors, opinion leaders can assume a variety of roles, including changing social norms and facilitating behavioral change. There is considerable variation in the methods used to identify opinion leaders for behavior change interventions, and these may have differential success. However, despite the potential consequences for intervention success, few studies have documented the processes for identifying, recruiting, and training opinion leaders to promote health, or have discussed the characteristics of those identified. One study that has acknowledged this is the effective UK-based ASSIST smoking-prevention program. The ASSIST Programme is an example of a peer-led intervention that has been shown to be successful in utilizing opinion leaders to influence health behaviors in schools. A “whole community” peer nomination process to identify opinion leaders underwent extensive developmental and piloting work prior to being administered in a randomized trial context. Influential students were identified through the use of three simple questions and trained as “peer supporters” to disseminate smoke-free messages through everyday conversations with their peers. In response to a need to understand the contribution of various elements of the intervention, and the degree to which these achieve their aim, a comprehensive assessment of the nomination process was conducted following intervention implementation. The nomination process was successful in identifying a diverse group of young people who represented a variety of social groups, and whom were predominantly considered suitable by their peers. The successful outcome of this approach demonstrates the importance of paying close attention to the design and development of strategies to identify opinion leaders. Importantly, the involvement of young people during the development phase may be key to increasing the effectiveness of peer education that relies on young people taking the lead role.