We examine the role of differentiation among competitive local exchange carriers (CLECs) in nearly 1,200 U.S. cities in 1999 and 2002, before and after a valuation crash affecting communications firms. We test and reject the null hypothesis of homogeneous competitors. We also find strong evidence that differentiated CLECs account for both potential market demand and the business strategies of competitors when making their entry decisions. Finally, product heterogeneity in markets in 1999 helps predict how the structure of markets evolved through 2002. We conclude that the policy debate for local telecommunications regulation should account for differentiated behavior.