The main goal of the article is to show how such new approaches as Mesoeconomics (ME) and Complexity Economics (CE) in economic analysis meet the challenges facing modern economic science. It is shown that the development of these approaches has been brought about by both practical needs and shifts in the system of paradigmatic scientific knowledge. Also shown are the differences between the initial assumptions of CE and ME, and the set of initial postulates of neoclassical mainstream economics. It is emphasized that CE and ME are based on modern ideas of self-organization of complex systems. At the same time, they restore the traditions of classical Political Economy, since they also consider the organic nature of the economy, evolutionism and historical conditioning. Both approaches explore the logic of the formation of economic mechanisms that create patterns of economic life and the spread of change. Along with the commonality of the approach from the ME perspective and the approach from the point of view of CE, their distinctive characteristics are identified, which allows them to complement each other. Comparison of ME and CE makes it possible to carry out a more in-depth analysis of the methodological features of mesoeconomic analysis, in comparison with the author's earlier works on this subject (Kirdina-Chandler, Maevsky, 2017; Kirdina-Chandler, 2018 – both in Russian).