It can be suggested that pre-service primary school teachers' sense of belonging to science may be influential to their professionalization within university-based teacher education programs, which intend to prepare them for teaching natural sciences in primary school. Nevertheless, because only few studies have examined teachers' sense of belonging to science so far, further research in this regard seems both reasonable and necessary. To this end, there is a need for instruments enabling a valid assessment of pre-service primary school teachers' sense of belonging to science. However, existing sense-of-belonging-to-science instruments require a comparatively long time on task due to their significant number of items. Consequently, the applicability of these instruments within research is limited because surveys in educational contexts must often be brief and economical. The research we present in this article aims to tackle this issue by examining on an exploratory level whether and to what extent pre-service primary school teachers' sense of belonging to science can be validly assessed using a single-item instrument. In doing so we report qualitative, as well as quantitative, findings that provide evidence regarding the validity of our instrument. Implications of the present study for future research are outlined at the end of this article.