General Equilibrium Theory has been one of the major intellectual developments in economics during the past half-century. The theory of general equilibrium is centred on an inquiry about human societies which has several of the characteristics of a fundamental scientific question. In an economy, a multitude of agents produce, exchange, and consume a large number of commodities. Their decisions are independent of each other and dictated by self-interest. Attempting to answer the question 'Why is social chaos not the result?' has required an intensive research effort by several generations of leading economists. This important three volume set gathers together many of the articles that have played an influential role in the history of ideas in the general equilibrium area in the contemporary period.