Two Tactics of Social Democracy in the Democratic Revolution is one of the most important of Lenin's early writings. It was written in June and July 1905, while the Russian Revolution of 1905 was taking place. Lenin's preface poses these questions: "in educating and organizing the working class;...where should we place the main political emphasis in this work of education and organization? On the trade unions and legally existing associations, or on an insurrection, on the work of creating a revolutionary army and a revolutionary government?"

The history of social democracy stretches back to the 19th-century socialist movement. It came to advocate an evolutionary and peaceful transition from capitalism to socialism, using established political processes, in contrast to the revolutionary socialist approach to transition associated with orthodox Marxism. In the early post-war era in Western Europe, social democratic parties rejected the Stalinist political and economic model then-current in the Soviet Union, committing themselves either to an alternative path to socialism or to a compromise between capitalism and socialism. In this period, social democrats embraced a mixed economy based on the predominance of private property, with only a minority of essential utilities and public services under public ownership. Social democrats promoted Keynesian economics, state interventionism, and the welfare state while placing less emphasis on the goal of replacing the capitalist system (factor markets, private property, and wage labor) with a qualitatively different socialist economic system.