ent access regimes by basing access rates on cost. The only plausible justification for basing regulated prices on costs incurred was that the absence of external markets caused by the lack of technological substitutes made it impossible to base rates on market prices. By stimulating direct facilities-based competition, the emergence of platform competition and the shift to access regulation have made market-based pricing both feasible and desirable. We refute arguments advanced by other scholars suggesting that network industries are somehow prone to unique forms of market failure that justify adhering to cost-based pricing. Economies of scale and scope, sunk costs, and network economic effects do not generally cause market prices to deviate from levels that promote efficiency and do not change the basic analysis. Finally, we examine the constitutional implications of the emergence of access regulation by evaluating the limits that the Takings Clause places on such reg- ulation. Because rate regulation simply restricts the terms and conditions under which parties may contract for finished goods and services, it represents the type of adjustment of economic burdens traditionally subject to the more permissive analysis applied to nonpossessory takings. Access regulation, in contrast, often requires network owners to permit third parties to place equipment on their prop- erty. When that is the case, access regulation necessarily falls within the Supreme Court's physical takings jurisprudence, which mandates that the government reim- burse property owners for the market value of their property without regard to the economic impact of the regulation or whether the regulation in question furthers important public interests. Therefore, when physical collocation is involved, just compensation for compelled access exactly corresponds to economically efficient prices for compelled access. Established principles of economics and constitutional law thus require that regulators adopt methodologies that allow voluntary access