One way for teachers to develop their professional learning, which also focuses on specific science content and the ways students learn such content, is through being involved in researching their own practice in a learning study. This article reports on a research project that aimed to develop science teachers’ PCK through their participation in a learning study. A learning study is a collegial process in which teachers are guided by a specific pedagogical theory, variation theory, and work together with a researcher to explore their own teaching activities to identify what is critical for their students’ learning. Another important aspect of the learning study is that it pays attention to how teachers’ collective construction of professional knowledge is enacted by making a shift from professional development as something that is done to teachers towards considerations of professional learning which entails work with and by teachers