Methodological Issues in Neoclassical and Behavioral Economics. This work describes how epistemological and methodological stances have been applied to economics; in particular the thesis' subject is the approach to two research programs, the neoclassical economics and the behavioral economics. Neoclassical economics is, nowadays, the dominating paradigm. The work depicts the evolution of its methodology, starting with Mill's narrow view of economics, passing through the economic approach to human behavior inspired by Friedman and terminating with the meaning of economic models. On the contrary, behavioral economics is a recently born paradigm whose original aim was to increase the realism in economic investigations.