The purpose of this three‐year naturalistic case study was to see whether collaborative reflection could enhance teaching and learning of science by generating desirable cognitive, metacognitive, and affective outcomes. Reflection was both individual and in groups, and involved reflection on practice in the classroom and phenomenological reflection on the nature of science teaching and learning. The study had two components. The preservice component involved 13 student teachers and teacher educators. The in‐service component involved 14 novice and experienced science teachers and 350 of their students. The authors worked with both groups to devise ways of changing classroom attitudes and behaviors of teachers and students. The voluminous data collected include records of many interviews, questionnaires, and written evaluations. Findings from the study illuminate aspects of the nature of science teaching and learning, processes by which individuals improve the quality of their practice, and methods for exploring teaching and learning mechanisms and facilitating change. Central to these findings is the importance of each of the two types of reflection for fostering personal and professional development. For both teachers and students, both types of reflection acted to improve their knowledge, awareness, and control of themselves and their classroom practice.