Abstract: The research subject of this article is the lifestyle transformation of the Old Believers in Buryatia at the beginning of the 20th century. The research object of this study is the Old Believer population in the Verkhneudinsky uyezd in the Transbaikal region (from 1923 - the Buryat Autonomous Soviet Socialist Republic). The authors consider such aspects of this topic as the trends that have changed the life of the uyezd's Old Believers; the attitude of different generations of Old Believers towards their way of living, the external influence on its isolated position (in the field of education, health care and religious morality), and the new attributes that came with the Soviet government (technological progress, emergence of youth organizations).The authors applied the historical-comparative method, which compared the aspects of various phenomena and revealed their general and particular features, upon examining the attitude of the Old Believers towards the activities of the tsarist and Soviet authorities. The historical-genetic method is necessary for examining the phenomenon under study in time in order to reveal the dynamics of the changes in the lifestyle of the Old Believers during the generational evolution. The results of the conducted study are the following. The decline of the traditional way of life among the Old Believers in Buryatia was a growing phenomenon, intensifying  from one generation to another. If for the Old Believers in the 18th - 19th centuries life in a community isolated from the external works was desirable and necessary to maintain their faith, then at the beginning of the 20th century this lifestyle became increasingly unacceptable, especially for the younger generations. The novelty of the authors' study is the introduction into scientific circulation of archival material that reveal the factors that caused significant changes in the perception of the world: the decrease in the role of the Old Believer religion in the life of young people, the acute need for education, the spread of a different way of life, and the struggle of the Soviet government with “remnants of the past” .