Rejecting the idea of an equilibrium business cycle, this book, originally published in 1927, studies those industrial fluctuations which extend over short spans of years: cyclical fluctuations. The causes of these cycles are discussed and the consequences which result and way in which to mitigate these consequences with regard to social well-being are examined. Although Pigou's approach went out of fashion following Keynes, it is similar in spirit to much of the late twentieth-century work stimulated by real business cycle theory.