The article is aimed at defining the place of behavioral economics in the paradigmatic structure of modern economic theory and its role in the development of modern economic knowledge. Poor attention of the classical economic theory to the behavioral aspect of decision-making by economic actors in the face of increasing instability and uncertainty of economic development has caused actualization and popularization of researches in the sphere of behavioral economics. It is emphasized that only the research construct of the theory of behavioral economics allows understanding of the irrational phenomena of economic behavior. Based on the identification of the general and distinctive characterizations of the neoclassical and the behavioral theories, as well as taking into account expert estimations, it is proved that the behavioral economics expands the theoretic and methodological basis of modern economic science through introduction of researches on the cognitive-psychological mods of the subject making economic decisions. It is defined that modern economic theory has a polyparadigmatic character, which is caused by the dominance of branching and heterogeneity of scientific interpretations of one and the same economic phenomena and problems. As a result, complex forms of coexistence and interaction of scientific paradigms are present and variations of interparadigmatic synthesis become possible, such as the active development of the theories of behavioral economics, e.g.: cognitive economics, neuroeconomics, etc. The development of behavioral economics takes place in cooperation with other modern economic theories (modern neoclassic, experimental economics, neo-institutional theory, evolutionary theory, etc.), but its applied potential is much greater, which transfers the behavioral economics from the scientific «periphery» to the «center» of the paradigmatic structure of modern economic theory.