Mixed families have historically been considered to be a direct consequence of a process of social and cultural integration of migrants within the host society, although this link has recently been problematized by scholars. By focusing on the case study of an association of “Christian-Muslim„ families in Belgium, this article offers a better understanding of the social consequences of mixedness. The article seeks to shed light on the private and public life of the couples who are members of this association by answering the following research questions: Why do couples turn to this association? At what stages of their lives? What is the social role that the association aims to play in society? Using partners’ life stories and ethnographic observation gathered during the association’s meetings, the findings demonstrate how this association plays an important role at different levels and at different stages of a family’s life. The analysis will highlight that: (1) there is a specific aim to help new couples to face administrative, religious and cultural “obstacles„ they encounter during the first period of their relationships, and (2) special meetings to discuss the challenge of parenting are at the core of the association’s activities. The “problem„ of transmission requires of the couple further negotiations to find a way to balance their respective cultural backgrounds. These negotiations have to take into account the power misbalance within the Belgian hegemonic context. (3) The social activism of this association is an important aspect of its aims and scope. Some of the couples are active in countering a dominant stereotypical representation of mixed couples. They organize meetings and events to sensitize public opinion on interreligious dialogue, migration issues and the fight against racism. In this way, the association proposes itself as a new peculiar agent of social change in the public sphere.