The objective of the study is to solve three interrelated problems: a) representation of published statistical collections containing information on agriculture in the BMASSR in the late 1920s – 1930s; b) construction of series of dynamics of the population of the main types of livestock, areas of crops and their organizational and production structure; c) reconstruction of trends in the development of agriculture in Buryatia in the study period. The object of the study is agriculture of the Buryat-Mongolian ASSR (BMASSR) in the late 1920s – 1930s. The basic sources for constructing the dynamic series are processed materials of statistical monitoring of agriculture published in regional and all-Union statistical collections. As additional sources, consolidated statistical materials extracted from the fund of the Central Statistical Survey of the Russian State Archive of Anthropology and Ethnography are used. The information used is the result of processing mass sources obtained in the course of state statistical monitoring. In the 1920s the accounting of basic quantitative indicators of peasant farms, including sown areas and livestock numbers, was carried out within the framework of selective comprehensive agricultural censuses. In the late 1920s, comprehensive surveys of collective and state farms were conducted. After the start of collectivization, the agricultural statistics system that had been in operation in the previous period was abolished. The main method of statistical monitoring in the early 1930s was tax and departmental accounting. In the middle of the decade, the non-departmental system of agricultural statistics was recreated. Since 1935, the annual final accounting of sown areas and all-Union livestock censuses in farms of all categories were assigned to the national economic accounting bodies. The results of statistical monitoring of agriculture were processed by the republican, regional and provincial departments of national economic accounting, and then sent to the Central National Economic Administration, where adjustments could be made. The indicators of individual dynamic series are comparable in terms of the range of objects covered and geographical boundaries. Their analysis allows us to determine the parameters of agricultural development in the BMASSR. Collectivization led to a crisis in livestock farming, which was not overcome until the end of the 1930s. In crop production, there was a significant increase in sown areas. Collective farms became the main producers of agricultural products. Private household plots of the population made a significant contribution to the production of milk, potatoes and meat.