Much experimental evidence indicates that choice depends on the status quo or reference level: changes of reference point often lead to reversals of preference. The authors present a reference-dependent theory of consumer choice, which explains such effects by a deformation of indifference curves about the reference point. The central assumption of the theory is that losses and disadvantages have greater impact on preferences than gains and advantages. Implications of loss aversion for economic behavior are considered. Copyright 1991, the President and Fellows of Harvard College and the Massachusetts Institute of Technology.