Nearly a century ago, the historian R. H. Tawney wrote an identically titled book about the role of religion in the rise of the market economy. Tawney was responding to the German sociologist Max Weber, who famously argued that Calvinist religious thought had set the stage for the rise of capitalism. Although Friedman writes in the same tradition, his focus is different: he is concerned with the impact of religion not on the economy but on economic thought. He shows that a variant of Calvinism that emphasized human choice and action rather than predestination profoundly influenced Adam Smith, the Scottish political economist whose writings shaped modern economic analysis. Smith emphasized individual decision-making and the capacity of the market, as an aggregator of those decisions, to improve the human condition. Over time, the discipline of economics became more rigorous and quantitative, and the influence of religion tended to recede. Even today, however, there remains a connection between the religiosity that distinguishes the United States from other advanced economies and the almost pious belief of many Americans in the importance of human agency and the virtues of the market economy.