The purpose of this study was to investigate how 22 preservice science teachers' (PSTs') beliefs about teaching socioscientific issues (SSI) changed after experiencing SSI instruction and reflection from both a learner's perspective and a teacher's perspective during a 12-week initial teacher education course. The study also explored the learning experiences associated with these changes. This study was conducted in Hong Kong, where the science, technology, society and environment (STSE) framework has been integrated into the secondary science curriculum but no SSI instruction is provided. Data were collected through learning tasks completed by the participants: (a) curriculum designs (pre-, mid- and post-course), (b) lesson plans (mid- and post-course) and (c) weekly reflective journals. Six profiles characterising teaching beliefs about SSI emerged from the data analysis. Qualitative analysis showed that the teaching beliefs of the PSTs had shifted from the traditional view that SSI should not be covered in science education to embracing SSI teaching. Three illustrative cases were used to capture key learning experiences and explore how these had led to a change in beliefs over time. These cases explained how PSTs' reflection on the why, what and how of teaching SSI to students can shape their beliefs about teaching SSI. The results have implications for the development of a closer alignment between PST beliefs and the SSI paradigm. Copyright ©2021 Springer.