Monopoly Capital: An Essay on the American Economic and Social Order is a 1966 book by the Marxian economists Paul Sweezy and Paul A. Baran. It was published by Monthly Review Press. It made a major contribution to Marxian theory by shifting attention from the assumption of a competitive economy to the monopolistic economy associated with the giant corporations that dominate the modern accumulation process. Their work played a leading role in the intellectual development of the New Left in the 1960s and 1970s. As a review in the American Economic Review stated, it represented "the first serious attempt to extend Marx’s model of competitive capitalism to the new conditions of monopoly capitalism." It attracted renewed attention following the Great Recession.

Paul Marlor Sweezy was a Marxist economist, political activist, publisher, and founding editor of the long-running magazine Monthly Review. He is best remembered for his contributions to economic theory as one of the leading Marxian economists of the second half of the 20th century.