This paper investigates the (apparent) conflict between appeals to Pan-Islam transnationalism and religious nationalism in the Netherlands East Indies, between the 1920s and the 1950s. Analyzing the career and writings of S. M. Kartosuwiryo (1905-1962) —Sarekat Islam leader and founder of the Islamic State of Indonesia —the article argues that shifts from one ideological platform to the other functioned to rally support for the Islamic state project, in conjunction with historical contingencies.