Reform or Revolution, also titled Social Reform or Revolution?, is an 1899 pamphlet by Polish-German Marxist theorist Rosa Luxemburg, in which she argues that trade unions, reformist political parties, and the expansion of social democracy could not create a socialist society as Eduard Bernstein, among others, argued. She contends from a historical materialist perspective that capitalism is economically unsustainable and will eventually collapse and that a revolution is necessary to transform capitalism into socialism. The pamphlet was influential in revolutionary socialist circles and an important precursor to left communist theory.