Communism is both a body of theory and a set of twentieth-century regimes, and reading it in order matters because the gap between the idea and the history is where understanding lives. Founding texts, the revolutions they inspired, and the histories that reckon with the results: following the sequence lets you hold theory and practice together without collapsing one into the other.
The path below starts with the core ideas, moves through the great revolutions, then turns to the histories and their sober accounting. Read even-handedly and in order, it gives you both the vision and its record.
The founding ideas
Begin with Capital, the Communist manifesto and other writings, the essential Marx including the manifesto. Capital Volume I is the fuller analysis of capitalism, best read selectively, and Marx: A Very Short Introduction by Peter Singer is an excellent brief guide if you want orientation first. The state and revolution by Lenin then presents the theory of the revolutionary state.
The revolutions and the reckoning
History follows theory. A people's tragedy by Orlando Figes is the acclaimed narrative of the Russian Revolution, and The Gulag Archipelago by Aleksandr Solzhenitsyn is the searing firsthand testimony of the Soviet camps. Mao by Jung Chang and Jon Halliday is a fierce, contested biography of the Chinese leader.
For the broad view, The age of extremes by Eric Hobsbawm offers a magisterial, sympathetic history of the century, The Black Book of Communism compiles a controversial accounting of the death toll, and The Rise and Fall of Communism by Archie Brown is a balanced scholarly survey. Reading the last three together gives you the range of serious interpretation. Follow the full path to read them in order.