New Classical Macroeconomics (NCM) arise from the development of the neoclassical economics principles, such as market clearing and optimization behavior by economic agents, which relate this school to monetarism. Its rise as a doctrine can be traced to the work in the early 1970s of its lead economist Robert Lucas (Chicago School).
Indeed, Lucas developed in 1973 what is known as rational expectations, an improvement on the adaptive expectations hypothesis used by monetarists, which changed the way macroeconomic analysis (and econometric analysis) is undertaken. These rational expectations are still used nowadays in macroeconomics.
Regarding policymaking, the NCM believes that no government intervention concerning demand is beneficial for the economy, not even in the short run. They argue that government can promote growth and stabilize the economy only through supply-side policies.
Economists such as Thomas Sargent, Edward Prescott, Neil Wallace and Robert Barro are amongst the most renowned NCM economists, whose theories are usually opposed to those of the followers of New Keynesian Economics.