Background: An in-depth understanding of pre-service primary teachers' progression towards teaching science through inquiry is critical for improving teacher education programmes and, ultimately, improving the quality of science teaching and learning in the classroom. Purpose: This study set out to describe and analyse the progression of pre-service primary teachers' learning during an initial teacher education course on how to teach science through inquiry. There was a specific focus on the progression of learning in the area of curriculum content as a component of pedagogical content knowledge (PCK). Method: The sample consisted of 347 pre-service primary teachers grouped into 92 teams. As a component of their pre-service training, they were designing science teaching proposals as part of the course on teaching science through inquiry. An analysis was conducted to explore the content of the designs created by these teams, both at the beginning and end of the course. Data were analysed qualitatively, using an interpretative approach informed by grounded theory. Findings: The analysis identified that most of the teachers progressed in their learning throughout the course, although only 14 of the teams progressed in all categories. It was possible, through the analysis, to determine intermediate levels of learning, between the starting level and the highest level of PCK. The analysis also indicated that the change paths of each team were very different. Discussion and Conclusions: Our study suggested that it was possible to analyse the professional learning and knowledge of the pre-service primary teachers in terms of progression in their learning of how to teach science through inquiry. Identifying progression in learning is complex and nuanced. However, we believe that this endeavour is an important underpinning research activity in order to support improvement in initial teacher education in primary science.