Religious harmony is an idea more commonly invoked in Asian countries, many of which are closely associated with non-individualistic or non-liberal approaches to law, ethics, and politics, than in Europe. As a constitutional norm, religious harmony not only directs state action involving the management of religious diversity but also has the potential to legitimate state action. As a result, harmony, including its subspecies of religious harmony, could be and has been criticized for imposing and legitimating an ideology of control over society, particularly over marginalized groups. While this is the case, I argue in this Article that religious harmony can mean many things and can be used in a myriad of ways that go beyond simply as a tool for state control. Religious harmony is not only a legal/constitutional principle, but has also become internalized as a social norm. Its regulating function extends to inter group relations and further grounds group demands on the state, thus imposing state obligations. To draw out the multiple and complex dimensions of religious harmony as a constitutional principle and social norm, I use Singapore, a self-avowed non-liberal communitarian state, as the primary case study in this Article.