This paper examines the concept of (public) sin as well as efforts to counteract sin from the perspective of Islam. The understanding that hisba, the prohibition of vice and enjoining of virtues, are a responsibility of both the state and the community is common in historical and contemporary Muslim societies. Where the state cannot or does not provide means for countering (public) sin, the perception for some Muslims is that the responsibility on the community and individuals to do so increases. Based on ethnographic research in Britain, Nigeria, Indonesia, Malaysia, and Singapore, the paper highlights examples of how sin has been defined amongst Muslim communities as well as the methods and rationales given to justify the forbidd...