This paper reports on a study undertaken to investigate international perspectives of what constitutes research in education for sustainable development (ESD). By employing inductive thematic content analysis, the authors sought to examine the perceptions of 66 ESD researchers from 19 countries. The findings reveal a concern with the methodological aspects of research and an emergent need for synergy between the methodology of educational research and specific themes relevant to ESD research. The significant overlap of themes and aspects of ESD research apparent across the different contexts within which the researchers were embedded indicates a unified core of ESD research, although there is also evidence of contextual factors influencing the research agenda. Based on the findings of this study, the paper concludes that there is an overlap between educational research and ESD research, but that the latter has its own specific aims, themes and political supporters. In an endeavour to develop a shared understanding about ESD research across disciplines and research context, a common language has to be developed to facilitate a constructive dialogue and research capacity building in this novel field.