The resolution of issues related to migration and immigration is one of the top priorities that the state and society must currently address. The Catholic Church has expressed its particular concern for migrants early on. Corresponding legal norms have been established and specific structures created for pastoral care in the mother tongue. This doctoral thesis examines the canonical status and pastoral situation of Catholic communities of different mother tongues in the German dioceses, addressing the pastoral care for Catholic migrants in the context of European and German migration policy. In light of declining numbers of priests and church tax revenues, pastoral care in the mother tongue is under scrutiny. There is also a discussion about integration within the Catholic Church.