This paper reports on a study which was designed to examine how CoRes (Content Representations) and PaP-eRs (Pedagogical and Professional-experience Repertoires) might impact the practice of science teachers by considering how they might value (or not) pedagogical content knowledge (PCK) as part of their professional knowledge. The paper is based on a 2 year longitudinal study that used CoRes and PaP-eRs as a form of intervention with a group of teachers (n = 6) to determine how they interpreted, used and developed their understanding of PCK over time. The study concluded that the participating teachers developed rich understandings of their professional knowledge of science teaching and were of the view that CoRes and PaP-eRs were significant in shaping that development. As a consequence, the study also validates the use of CoRes and PaP-eRs as a meaningful methodology for examining science teachers' PCK.