This paper presents the conceptual contours of the Emmy Noether Research Group project “The Bureaucratization of Islam and its Socio-Legal Dimensions in Southeast Asia”. The project views the bureaucratization of Islam not simply as a formalization, expansion, and diversification of Islamic institutions, but as a social phenomenon that far transcends its organizational boundaries and informs dynamics of social and cultural change alongside transformations of the very meaning(s) of Islam in state and society. It places the state’s “classificatory power” and its societal co-production and contestation at the centre of attention and aims to synthesize functional approaches with hermeneutic modes of analysis. While the bureaucratization of Islam is always embedded in and shaped by power-political constellations and political processes, it simultaneously produces social and doctrinal meanings that are unique to its specific discursive arenas.The paper first introduces the anthropology of bureaucracy and elaborates on the absence of studies from this field on state-Islam relations in Southeast Asia; it also considers the potential of bringing these two streams of scholarship into a fruitful dialogue. Second, it presents a case study in Brunei, focusing particularly on Islamization policies, the bureaucratization of a national ideology, and their workings on the micro level. Third, the paper moves on to a regional comparison by illustrating how similar matters are treated very differently by Singapore’s Islamic bureaucracy, despite partially shared features. After a brief note on methodology, the paper concludes that the presented work, while anchored in Brunei and Singapore, has implications for a wider study across, and potentially beyond the region.