Changes in the structure of agriculture and income distribution among producers make parity prices obsolete indicators of farmer well-being. This report chronicles the history of parity, surveys critiques of parity, and discusses changes that might reduce price distortions resulting from the use of the parity concept. Possible changes include adjusting the parity price formula by redefining base period prices and treating interest and taxes differently. New standards of equity, including cost of production, marginal social cost, and parity income, are examined.