Initial teacher education (ITE) is being challenged internationally to prepare teachers with the understandings needed to teach an increasingly diverse student population. Science teachers need to prepare students with both conceptual and procedural understanding. The challenge is to prioritise a balance in ITE courses between theoretical perspectives, curriculum requirements, and pedagogical approaches. This paper presents results of a three-year longitudinal study from pre-service through two years of in-service teacher development, and provides an insight into how pre-service and early carrier teachers gain confidence in their subject matter and pedagogical content knowledge and the teaching strategies they implement.