Dissertation: My dissertation, Unsettled Islam: Virtuous Contention in European Mosques, is based on two and a half years of ethnographic research in two of Europe’s largest representative mosque communities (the East London Mosque and the Sehitlik Mosque, Berlin), as well as sixty semi-structured interviews. I argue that a Muslim caste has been created in Europe, resulting in extreme forms of social closure. I trace the historical development as well as indicators of this caste. And I analyze how Muslim communities respond to this caste status through what I term “virtuous contention.” Such collective responses become legible in mundane practices, determining gender relations, stances on ethno/racial diversity, de-radicalization strategies and engagement with technology. This entails not only articulating the agency of Muslim collectivities that effect broader public spheres, but also explaining both how and why some communities seek harmonization with mainstream society, whereas others seek increased differentiation from the mainstream.