The article offers an introduction to the economic and sociological theory of Vilfredo Pareto. The author discusses Pareto's general equilibrium theory as well as his ordinalist utility theory including what is known as 'Pareto optimum'. In the sociological field, author focuses on Pareto's original theory of social stratification founded on the assumption of circulating elites. With this concept, Pareto not only opposed the Marxist concept, which optimistically predicted emergence of a class-free society, but he also opposed the liberal-democratic notion, which somewhat naively perceived democracy as the rule of people, by people and for people. The critical scrutiny of Pareto's major works leads author to the conclusion that Pareto's work, despite certain shifts in his opinions on the matters of elites and democracy, is methodologically compact and devoted to the issues of perseverance of societal and economic equilibrium.