This chapter explores the development of the interfaith movement in Singapore in terms of social movement theory, with particular attention to the Inter-Religious Organisation of Singapore (IRO). Two key frames for understanding the current situation are introduced, which are ‘embedded autonomy’ and ‘precarious toleration’. The former refers to the way that the interfaith movement is embedded and restricted by tight government regulation and management, yet still allows place for meaningful autonomous action by interfaith actors. The latter is a framing that highlights an ambiguous aspect of Singapore’s interfaith narrative, which is the success story of harmony, by positing that animosity and hostility across religious lines requires tight state control. The chapter explores the development of the IRO that began life as an activist social movement, but was gradually institutionalised, and, after 9/11, subsumed into the securitised framing of the interfaith agenda. It also includes discussion of more recent grassroots and often youth-led interfaith initiatives.