Examining the ambiguous concept of usury, this article retraces political battles over the epistemic framings of the everyday economy in the nineteenth century. It takes a comparative approach to the legal and economic debates on usury in the Habsburg and the German empires in the wake of the economic crisis of the late 1870s, when new laws against usury were introduced. In the respective debates, diverging political interests and class attitudes pitted different conceptualizations of economic exchange against each other. At stake were the diverse forms of commensuration and valuation scales in received credit practices. The new legislation on usury centred on the notion of a usurer’s victim who supposedly was incapable of rational economic action and thus in need of civilization. By way of conclusion, this article relates the story of nineteenth-century usury legislation to current debates among historians on capitalism and the emergence of the economy as a bounded entity. It argues for more analytical attention to historical conflicts over modes of exchange as they came to the fore in the debates on usury, and discusses the implications of this perspective for the history of economic liberalism.