The U.S. paper industry has become increasingly concentrated and therefore been suspected of imperfect competition. In this study, the new empirical industrial organization approach is employed to measure the degree of oligopoly and oligopsony power in the U.S. paper industry simultaneously. The model is estimated by iterative three-stage least squares using annual data from 1955 to 2003. The results reveal that there has been significant oligopoly and oligopsony power in the U.S. paper industry, and the oligopoly power has been consistently lower than the oligopsony power.