Abstract: The history of economics has often overlooked the evolution of classical political economy from Smith's tradition to Mill's system,particularly the utilitarian turn of economics in the 19th century.This turn had a significant impact on economics in two ways: From a normative perspective,the utilitarian moral theory moved morality behind the scenes,and laid solid foundations for economic analysis based on interests.Whereas from a positive perspective,associationist psychology enabled science to take the stage,offering a behavioral model built on methodological individualism.The utilitarian turn in economics in the 19th century foreshadowed the inevitable evolution of the discipline from classical political economy to neoclassical economics.It also revealed the choices that modern economics has made and the price it has paid.