In this case study, teacher inquiry groups from 3 school districts engaged and transformed various facets of their professional knowledge and practice in the context of science education. To examine the nature of teacher learning, a 3-part teacher knowledge and learning framework, proposed by Cochran-Smith and Lytle in 1999, was adopted (knowledge-for-practice, knowledge-in-practice, and knowledge-of-practice). While 16 school-based inquiry groups participated in the collaborative action research project, one case study involving a primary teacher, Katrina, is highlighted to illustrate outcomes related to the role of collaborative inquiry in supporting teacher learning, contextual issues and concerns that impact teachers' daily classroom practice, and the types of knowledge generated by teachers within collaborative inquiry communities.