Objectives: This paper reviews why tensions between service and education persist and highlights that this is an area of medical education research (MER) that, to date, lacks a robust body of theory-driven research. After carrying out a review of the literature on service–education tensions in medical education and training, we turn to consider how theory can help provide new insights into service–education tensions. Methods: We conducted a search of the literature on service–education tensions since 1998 to examine the use of theory in studies on this topic. Results: We identified 44 out of 603 relevant papers. Their focus fell into four broad categories: time residents spent on ‘service’ and ‘education’; perceptions of the balance between service and education; considerations of how best to define service and education, and the impact of structural and systems changes on education/training. Of the papers reporting primary research, the dominant methodology was the bespoke survey. Rarely were the precise natures of tensions or how different factors interact to cause tensions examined in detail. Discussion: Through discussion and reflection, we then agreed on the applicability of four sociocultural theories for illuminating some examples of service–education tensions. We present four sociocultural theories: Holland's figured worlds, Kemmis et al.'s practice architectures, Lave and Wenger's situated learning and Engeström's cultural-historical activity theory (CHAT or AT). We describe each and then briefly illustrate how each theory can support new ways of thinking and potential directions for research focusing on education–service tensions. Conclusions: The use of theory in research studies will not resolve service–education tensions. However, what theory can do is illuminate and magnify different aspects of service–education tensions, to generate new insight and knowledge that can then be used to inform future research and changes in practice.