Peer-to-peer approaches engage groups of people considered to share one or more characteristics that identify them as peers and draw on rationales of credibility, identification and role modelling in peer-to-peer interactions. Despite the popularity of the approach, the ways in which the peer leadership component specifically contributes to health promotion is not thoroughly understood. We suggest that a first step for making use of peer leader characteristics is to make explicit what the peer leadership component is expected to bring to a programme. To approach such an understanding, we investigated how peer leaders can be supported in activating their ‘peerness’ in health promotion programmes, using as a case the peer leader education of a youth-led, peer-to-peer community sports programme, implemented by the non-profit street sports organization, GAME. We analysed the peer leader training programme’s learning objectives and field notes from observations of the training programme. The empirical material was analysed using an abductive approach by drawing upon contemporary interpretations of two forms of knowledge originally proposed by Aristotle. In so doing, this article explores how the development of techne (practical knowledge) and phronesis (practical wisdom) was supported in a peer leader training programme for young people. Findings suggest that supporting the development of both these types of knowledge can strengthen programme planners’ attention to the contribution of peers. Concurrently, an emphasis on promoting phronesis in peer leader training can support and encourage peer leaders in activating their ‘peerness’ in peer-to-peer health promotion programmes.