This paper describes a professional development model for developing science teacher leaders that has evolved and been refined through working with 16 high school chemistry and physics teachers in high-needs schools over the past 3 years. The theoretical framework draws upon Goodwin's notion of professional vision and Dempsey's four metaphors to inform an understanding of professional identity consistent with innovation and empowerment in (a) the classroom setting with students and (b) with teachers in collegial environments. Thus, leadership practices and purposes are discussed at two distinct levels and contexts, which interact reflexively. Sociolinguistic discourse analysis of multiple data sources enabled us to identify the professional development features that promoted or hindered the teachers' growth toward a leadership perspective and disposition. Implications for science teacher renewal and retention as well as limitations of the study and proposed leadership model are also shared and discussed.