The article gives an overview of the changes taking place during 1917 in the social structure of Russian society. Throughout 1917, three independent systems of organization and interaction between social groups had been distinguished: firstly, a fairly clear social division of society, traditional for Russia and preserved until the fall of the monarchy; secondly, a noticeable erosion of the class structure of the population during the period of the Provisional Government and the Soviets, which led to the formalization of class distinctions; thirdly, a new class division of society was observed for the country as one of the natural results of the October Revolution of 1917. During the period under review, one of the aspects of social inequality was transformed: inequality in the scope of the rights and freedoms of different social groups. Three different models for determining the legal status of the population were identified. In the monarchical period of 1917, there were quite profound differences in the scope of the rights of subjects – the estate principle laid at the heart of inequality. At the stage of the existence of a democratic republic, the class principle of inequality remained, but the difference in the scope of rights and freedoms was actively erased. The Soviet Republic switched to the class principle of social inequality, and deepened the difference in the legal status of classes to the ultimate level. The rate of such changes is completely uncharacteristic of the social structure and is explained by a whole complex of assumptions that provoked an incredibly fast and radical transformation that can be traced throughout 1917.