In German primary schools, natural sciences and social studies are learned and taught in an integrative manner within a subject called Sachunterricht. To teach Sachunterricht in a high-quality manner, it is reasonable to assume that primary school teachers themselves require-- among other things, such as knowledge about pedagogy, teaching Sachunterricht, and the various content areas of Sachunterricht--a distinct interest, academic self-concept, and sense of belonging regarding natural and social sciences. Furthermore, they should possess a solid interdisciplinary competence that enables them to teach natural and social sciences in an integrative way. In the present study, we conducted a longitudinal survey of pre-service primary school teachers from a German university over a period of 2 years to investigate the changes in their (self-evaluated) interdisciplinary competence; the changes in their interest, academic self-concept, and sense of belonging regarding natural and social sciences; and the correlations between these constructs. Our data analysis revealed a decrease over time in participants' sense of belonging to natural and social sciences, as well as their (self-evaluated) interdisciplinary competence, while their academic self-concept in natural and social sciences remained stable. Participants' interest in social sciences decreased, while their interest in natural sciences increased. Moreover, we found varying degrees of correlation between these constructs. In summary, the results of the present study provide important insights into the professional development of pre-service primary school teachers within university-based teacher education for teaching natural and social sciences in primary school. The implications of these findings are discussed in detail at the end of this paper.