This chapter deals with the new phase of the New Chicago School, characterized by the transition from Milton Friedman’s monetarist counterrevolution to Robert Lucas’s New Classical Macroeconomics. This shift involved numerous economists affiliated with the University of Chicago or connected institutions such as the University of Minnesota and the University of Pennsylvania—among them Edward Prescott, Finn Kydland, Thomas Sargent, Neil Wallace, and Robert Barro. Firstly, the chapter examines the contributions of Robert Lucas, who played the preeminent role in the development of New classical macroeconomic theory. The chapter then analyzes the implementation and evolution of Lucas’s research program, from the real business cycle model advanced by Prescott and Kydland to the development of DGSE Models and the emergence of the “New Neoclassical Synthesis” which combines elements of both New Classical and new Keynesian economics.