Abstract: The article is devoted to the study of the interactions between the Bolsheviks and Left Socialist-Revolutionaries in local soviets (councils) in the spring and summer of 1918. The subject of the article is the conflicts and clashes of the representatives of the two parties in the executive committees of Soviets at various levels. The investigation of these events is important for understanding the specifics of the Soviet state-political system in the first half of 1918, when the predominance of representatives of the Bolsheviks and the Left SRs in the Soviets and their influence allow us to speak of an unfolding two-party system in a number of provinces in Central Russia. In the article, on the basis of an analysis of a variety of archival documents and published material, the conflicts and their consequences on the existence of the two-party system within the executive committees of provincial and district Soviets are examined. The study of the interactions of the Bolsheviks and the Left Socialist-Revolutionaries implies the application of the basic methods and principles of historical research: historical-genetic, historical-typological methods, as well as the principles of historicism and objectivity. The novelty of the study consists of examining the practices of joint state activity of the Bolsheviks and Left SRs, as well as in defining the types of their conflicts. The author comes to the conclusion that the conflicts between the Bolsheviks and the Left Socialist-Revolutionaries were an important feature of the two-party system, since they allowed representatives of both parties to openly express their positions on internal political issues and make compromise decisions, all of which led to a certain balance of interests between the Bolsheviks and the Left SRs at the regional level. Ultimately, however, the increase in the number of conflicts between the Bolsheviks and the Left SRs contributed to the collapse of the Soviet two-party system.