Science education starts at primary school. Yet, recent research shows primary school teachers lack confidence and competence in teaching science (Prinsley & Johnston, 2015). A Victorian state government science specialist initiative responded to this concern by providing professional learning programs to schools across Victoria. Drawing on cultural historical activity theory (CHAT), this paper reports the analysis of transcripts of interviews with 17 science specialists from eleven schools. It presents the various perceived and enacted science specialist roles, and how they changed over time. The CHAT analysis of the transcripts revealed seven different stages describing trajectories of the science specialism. The variation in the trajectories indicate the importance of the influence of the community in the enactment of the science specialism. Affordances, constraints and challenges of implementing the science specialist role are discussed.