On the basis of ethnographic fieldwork carried out among youths living in Montreal (Canada) who are interested in Islam and adopt some elements of a Muslim lifestyle, I show how affinities with Islam arise from sociability practices with friends of Muslim background and relate to the cultural diversification of secular societies. By combining network analysis with narrative analysis, I examine how youths interpret and make sense of these interactions and propose a critical view of their cosmopolitan discourses. While the latter is grounded in a universalist rhetoric, I argue it also unfolds within the intimacy of sociability experiences and shared emotions. Youth’s cosmopolitanism draws on cultural repertoires that stem from public education programs and local strategies to promote peaceable cohabitation in secular contexts. Consequently, youth competencies for cosmopolitanism lead to ongoing conversations that make differences and divergences within sociability spaces new sites to negotiate intercultural encounters in highly diversified localities.