MARGARET E. GUERIN-CALVERT is Assistant Chief of the Economic Regulatory Section of the U.S. Department of Justice's Antitrust Division. She has a wide-ranging background as both a private consultant and a government economist, and has published articles and papers in economics and policy journals.STEVEN S. WILDMAN is Associate Professor of Communication Studies at Northwestern University and Director of Northwestern's Program in Telecommunications Science, Management and Policy. He was previously a private consultant to a variety of firms in the communications industry. He is a widely-published author of books and articles on communication industries.