The article discusses the influence of ethnic and religious factors on intercultural interactions in Samara Trans-Volga region in the second half of the 19th – early 20th centuries. The analysis of inter-ethnic contacts was made taking into account the national and confessional composition of the region’s population and the nature of settlement in mixed villages and groups of villages. The study is based on archival and published sources, including statistical data, as well as on the author's field materials (Samara region, 1997–2018). Intercultural interaction in Samara Trans-Volga region has historically been determined not only by ethnic, but largely by religious differences of contacting groups. Ethnically and confessionally mixed settlements were the main platform for communication, ranging from mutual hostility and socio-cultural isolation to the assimilation of one community by another. Historically, Orthodoxy and Islam acted as factors in consolidating ethnic groups within confessions in the region and, at the same time, as the reasons for the destruction of ethnic “boundaries” and formation of supra-ethnic sociocultural spaces (temple, cemetery, rural settlement, family-related circle, common holidays and rituals, etc.). Such an orientation of the religious factor resulted in assimilation processes (russification of the Mordovians and the Chuvash, tatarization of the Chuvash, etc.). At the same time, confessional differences separated ethnic groups and / or parts of one group, contributed to their relative mutual socio-cultural isolation, while maintaining the necessary level of intergroup communication in industrial and social spheres. Perception of confessional differences varied from tolerance to open hostility and enmity. These patterns of influence of the religious factor on the development of inter-ethnic relations are still relevant today.