The article contains the main historical sources identified in order to study the preparation and conduct of elections to the All-Russian Constituent Assembly in the Kaluga province. Despite the extensive amount of research available, most of them are conducted by the interests and ideas of the Russian Social Democratic Party (Bolsheviks). The problems of holding the first all-Russian vote in the regions are not covered enough. Only since the 1990s. we can talk about the emergence of a variety of problems raised by researchers related to elections to the Constituent Assembly. The author identified the following groups of sources of an all-Russian and regional nature: legislative materials, office documentation of central and local bodies responsible for the preparation and conduct of elections, collections of documents of political parties and public organizations, journalistic works of representatives of political parties, sources of personal origin, periodical printing. One of the cases of the fund of the F-1128 State Archive of the Kaluga Region "Protocols of the Meshchovskaya District for Elections to the Constituent Assembly of the Commission" deserves special attention, since it is the only source identified at the moment containing a detailed report on the conduct of elections in the county. The author believes that due to the fragmentation of regional sources, the absence of specially formed groups of documents in regional archives, only a comprehensive study of regional and all-Russian sources will allow us to study in detail the process of preparing and holding elections to the All-Russian Constituent Assembly in a separate constituency. A necessary condition for further research of the electoral process in the Kaluga constituency is the expansion of the source base through the materials of archives neighboring the Kaluga provinces, work to identify sources of personal origin.