For several decades, U.S. policy in telecommunications and electronic mass media focused on the encouragement of competition. This policy, usually known as deregulation but more accurately described as liberalization, is aimed at an opening of the market to competitors and a reduction of market power. There were numerous elements and proceedings to this policy by the Federal Communications Commission, the states? public service commissions and legislatures, the courts, and Congress. Of these actions, none was more comprehensive than the Telecommunications Act of 1996. What has been the impact of this policy? In this essay, I will focus on one dimension: the impact of liberalization on market concentration. This question has acquired some urgency in light of the meltdown in the telecommunications sector following the boom years of the 1990s. That downturn may be temporary, and the industry will recover. But the more fundamental issue is that the telecommunications industry may have entered into a pattern of boom-bust cycles.