Inequity theory differs from social exchange theory in its analysis of a worker's reaction to pay by asserting that effects on work performance caused by high or low pay are due to social comparison of fairness rather than principles of direct exchange, such as reciprocity and power. The present experiment held piece-rate pay constant at two levels and varied relative pay (80% higher, the same, 80% lower) reported by co-workers. Significant manipulation checks for relative pay were obtained. Significant performance differences for quantity and fewer pieces for lower relative piece-rate pay, were opposite predictions from inequity theory. No significant effects were obtained for quality, but the pattern of means was also the reverse of inequity theory predictions. This finding of effects due to social comparison which are the reverse of predictions from inequity theory raises questions both for inequity theory and for the portions of the more general equity theory which rely on social comparison processes. (Author)