This dissertation examines the macroeconomic impact of reduced labor market friction on the U.S. business cycle after the mid-1980s. The first two essays investigate the relationship between labor market flexibility and macroeconomic stability from a post-Keynesian perspective. In the third essay which reviews the relationship between labor market flexibility and patterns of U.S. business cycle, I test the argument that after 1985 Okun’s coefficient became larger due to the flexible labor market. In essay 1, considering two aspects of labor market flexibility, employment flexibility and real wage flexibility, I adopt the flex-output model (Skott, 2015) to first discuss employment flexibility and then extend it by incorporating real wage dyn...