When it comes to implementing educational policy changes, teacher leaders have been identified as playing a critical role. Yet, despite more calls for increased teacher professionalism and leadership, we lack substantial empirical research on how these teacher leaders are developed and the role of collaborative relationships in their development. The purpose of this study is to describe and explain what science teacher participants experience in a community of practice for implementation of NGSS and support for their teacher leadership. This basic interpretive qualitative study, draws on ethnographic and case study methods of observation and interview to address the research question, "How do science teacher leaders' experiences within a community of teachers and leaders influence their identity development?"