Leadership has been identified as an important influence on the provision of primary physical education (PE) in several different contexts. To date, however, there is a lack of data explicitly investigating informal PE leadership provided by generalist teachers in primary schools. Accordingly, this research sought to explore generalist teachers' experiences of informal PE leadership while promoting an innovation in primary PE. Five generalist primary school teachers in five separate schools led the implementation of an eight-week module of ultimate frisbee with their own class and provided support to two other class teachers within the school. Data was generated through qualitative methods including interviews with the lead teachers, focus groups with participating teachers involved in each school and weekly written reflections by the lead teacher. These data were analysed using reflexive thematic analysis [Braun, Virginia, and Victoria Clarke. 2019. "Reflecting on Reflexive Thematic Analysis." "Qualitative Research in Sport, Exercise and Health" 11 (4): 589-597. doi:10.1080/2159676X.2019.1628806]. Using [Hargreaves, A., and M. Fullan. 2012. "Professional Capital: Transforming Teaching in Every School." New York: Teachers College Press/Routledge] theory of professional capital as a theoretical lens the results provide insight into informal leadership actions, the factors which influenced these actions as well as the importance of a shared approach to leadership. Overall the results of this research suggest that informal PE leadership can play an important role in supporting innovation.