Sweden is considered to be one of the most secular countries when measuring items such as church service attendance, expressed beliefs in God, and agreement with statements such as “religion is an important part of life,” compared to other countries in Europe and elsewhere. Official church attendance in major church congregations, such as the Church of Sweden and most other Protestant Free Churches, has shown a pattern of decrease in membership in modern times, with some congregations risking to disappear as a result. New configurations of social work practice are challenging current congregations with crossover-interfaith schemes, shared buildings, and community-oriented services with a field presence in marginalized urban areas, replacing homogeneous and diaconal or charitable work. Three cases of interreligious social work are analyzed, and in particular the social and religious leadership skills required for collaboration between the religious communities as well as the surrounding society. The interreligious social work practice is also an important factor of social service provision in the concerned local communities and has strengthened the role of religion in the social sphere in what can be expressed as a postsecular Sweden.