Using the data from the 1989 and 2002 censuses, the author examined the peculiarities of the marriage and family relations formation in Bashkortostan under the conditions of ethnic diversity. Ethno-demographic processes in the marriage and family sphere are of great importance, they contribute to the interpretation of the model of demographic behavior of the main ethnic groups and allow to identify characteristic features and problems. In turn, a person's belonging to a certain culture determines his behavioral pattern, the form of intra-family communication and affects the formation of marriage and family relations in general. The ethnic factor is essential in analyzing the processes of natural population movement. At the same time, external factors have a significant impact on the development of ethno-demographic processes: the processes of the social structure modernization. In this regard, the analysis of ethno-demographic processes in the family and marriage relations formation will make it possible to determine reproductive attitudes, the place and role of family values in the hierarchy of values, and the impact of external factors on the traditional norms of marital behavior. The chronological framework of the research is 1989 — early 2000s.