A majority of educators are ill-prepared to teach culturally relevant and reform-based science, especially in socioeconomically-stressed, diverse urban settings. Inadequate teacher quality has contributed to an annual inequality for historically-excluded students that has accumulated to create a long-term disparity. The purpose of this qualitative, comparative case study was to address these inequities by creating a science professional development intervention for elementary educators teaching at two socioeconomically-stressed, highly diverse urban schools. My aim was to positively influence their science teaching identities in order to improve students' learning experiences. Seventeen teachers participated in the year-long professional learning community and focused on a phenomenon-based science teaching approach: Ambitious Science Teaching (AST). I interviewed, surveyed, and observed the teachers in order to see the impacts of the intervention. My research questions were (1) How does a Professional Learning Community focused on a phenomenon-based science teaching framework affect elementary educators' science teaching identities –self-efficacies, beliefs, and practices? And (2) How do these influences relate to and reflect particular school contexts and teacher characteristics? I found that the elementary educators' contexts influenced their experiences with the intervention and overall, their science teaching identities improved throughout their participation. The AST framework opened their eyes to the essential importance of student-centered science and deepened their concern about the district-adopted curriculum, FOSS, which they understood -- contrary to its intent and claim -- to be a constraint on their teaching.