Bottom-up transformationThe role of religious public within ecclesiastic multi-level systems Abstract Churches are not as change-resistant as they may seem at first sight. Rather diffuses social change into ecclesiastic social forms through the autonomy of professions as well as through the increased involvement of the religious public-which can be described as a bottom-up transformation. However, established sociological terms and approaches have proven to be inadequate to directly and fully capture complex and singular social forms of religion, such as the Catholic Church, and its change. With regard to this situation, an analytical subdivision into distinct levels of church would seem appropriate. In this sense, ecclesiastic social forms are to be understood as multi-level systems. In this paper, their inherent dissociation of functional logics and action orientations is discussed citing an empirical example stemming from Catholic liturgy: church services, which are no longer conducted by priests, but by lay persons (so called "Services of the Word"). Such church services can be seen as an activation of the religious public, which is entailing an individualization and pluralization of ecclesiastical offers. Thus, not only would individualization and pluralization seem to be transformations of the social environment, thereby contributing to a de-churching, but also processes of change within the church itself. In view of the above, ecclesiastical social forms retain a function that is not to be underestimated: ensuring the evidence of an individualized faith, which is increasingly perceived as contingent.