The public visibility of Islam reveals new political stakes in European democracies around issues of immigration and citizenship. By focusing on the societal debates and the controversies around the construction of mosques and minarets, this article explores the ways in which Islamic difference is manifested, perceived and framed in public life. The "visibility" of Islam in public is conceptualized as a form of agency, a manifestation of religious difference that cannot be thought independent of the materiality of culture, namely aesthetic forms, dress codes, or architectural genres. It is argued that the debates for or against the banning of the construction of mosques and/or minarets reveal the tumultuous transition of Muslims from the status of the invisible migrant-worker to that of visibly Muslim citizenship. The public visibility is approached therefore as a radically disruptive, transgressive, provocative form of transformative agency that is intrinsically related to the political process of becoming citizens.