The present monograph provides a comprehensive study of recent evolutions and future trends in economics, which is directed towards an ambitious objective: to assess the present state of economic science, particularly in the context of the global crisis. We set out to investigate the most important evolutions which marked economic theory and practice after World War II, and particularly during the past four decades. Theoretical progress has been significant, including such issues as: the micro foundations of macroeconomics, rational expectations, market-clearing models, market imperfections, monetary neutrality or business cycle theories. However, the impact of theoretical progress on policy has been rather low, as economists have not radically changed the way they analyze the economy. The analysis goes on to present the two main streams of thought that dominate current economic analysis ? the New Classical School and New Keynesian Economics. In light of recent evolutions, the natural conclusion is that economic science is not going through a crisis, but is rather experiencing periods of slow progress or stagnation, marked by economists' fervent searches for a new paradigm.