Why do Sundanese Muslims of West Java in certain situations prefer Islamic oratory in their regional language, Sundanese, and in others prefer the national standard, Indonesian? This article answers this question by firstly exploring different preaching outcomes that are recognised and generally accepted by Sundanese Muslims. Some preaching events are oriented pre-eminently to the communication of affect within the temporal frame of co-presence. In others, preacher and audience unite around a transformative ethos. These outcomes bear contrasting implications for code selection. Where the first outcome is desired, preachers display multivocal, heterogeneous preaching styles in which the regional language offers functional benefits. In the second, Indonesian preachers and audiences respond to the national language's indexing of transformation. The social value of transformation is a situational factor for which Indonesian is the appropriate code. In this way, code selection signals the diversity of ways of being Islamic in the West Javanese public sphere.