This article argues for a transregional historical approach to explain the career of political secularism, i.e. the ideas and practices that inform the modern state’s relationship to and administration of religion, in the 20th century. More specifically, it asks in how far we can understand secularism in South and Southeast Asia between the end of the First World War and decolonisation after 1945 as a result of transregional patterns that evolved within and beyond these regions. The argument is based on (...) three brief case studies on Atatürk’s Turkey as a contested source of inspiration for state secularity and religious reform, regional women’s networks to foster secularism and social change in the 1930s, and secularism as a strategy of postcolonial state-building and territorial integration. Conceptually, the article suggests to use global intellectual history as a means to combine research on connectivity with historical comparison. (shrink)