European social democracy is at once a political theory, a political movement, and a set of institutions. As a political theory, European social democracy has its origins in the development of the workers’ movement, inspired by Marxist and utopian socialist ideas, in the second half of the 19th century. This movement spawned political parties with the label “social democratic,” “socialist,” or “labor” in practically every European country, and these parties mobilized industrial and agricultural workers as well as intellectuals in opposition to capitalism and political authoritarianism. Social democracy as a distinct political force emerged out of the split in the workers’ movement between revolutionary socialists and those who sought to achieve socialism through a parliamentary route. This split was formalized in the wake of the Bolshevik revolution in Russia, with revolutionaries creating separate Communist parties while the rump of the workers’ movement adopted a gradualist or revisionist strategy of reforming capitalism through democratic institutions. Social democratic parties went on to establish themselves as mainstream political forces, participating in government or forming the main opposition, in almost every European country. Where social democrats were electorally successful, they were able to promote institutions such as the welfare state and corporatist bargaining in the workplace, and in some countries they brought parts of the private economy under government control. By the end of the 20th century, however, many European social democrats adopted increasingly promarket stances, arguing that globalization and technological change had rendered the classic social democratic model obsolete.