Common property rights were widespread in English agriculture for at least 600 years. Since privatizing common fields allegedly produced huge profits in the eighteenth century, common land owners seemingly squandered 15 percent of potential income for generations. Ingenious explanations have been produced for this market failure. This article argues for a simple, brutal resolution. Common fields survived because enclosure was generally unprofitable before 1750, when changing relative prices made private property rights marginally more efficient. Then people responded quickly to modest profits. The rich gains from enclosure existed only in the imaginings of wild-eyed eighteenth century agrarian reformers.