In 2013, as part of a process to renew an overall sector vision for science education, Catholic Education Melbourne (CEM) undertook a review of its existing teacher in-service professional development programs in science. This review led to some data analysis being conducted in relation to two of these programs where participant teachers were positioned as active learners undertaking critical reflection in relation to their science teaching practice. The conditions in these programs encouraged teachers to notice critical aspects of their teaching practice. The analysis illustrates that as teachers worked in this way, their understandings about effective science pedagogy began to shift, in particular, teachers recognised how their thinking not only influenced their professional practice but also ultimately shaped the quality of their students' learning. The data from these programs delivers compelling evidence of the learning experience from a teacher perspective. This article explores the impact of this experience on teacher thinking about the relationship between pedagogical choices and quality learning in science. The findings highlight that purposeful, teacher-centred in-service professional learning can significantly contribute to enabling teachers to think differently about science teaching and learning and ultimately become confident pedagogical leaders in science. The future of quality school-based science education therefore relies on a new vision for teacher professional learning, where practice explicitly recognises, values and attends to teachers as professionals and supports them to articulate and share the professional knowledge they have about effective science teaching practice.