Previous theory and research on exchange relationships offer conflicting predictions about how givers and receivers evaluate episodes of favor exchange. Whereas studies of egocentric biases suggest that favors are valued more by givers than by receivers, theory and research on interpersonal interaction norms suggest instead that favors are initially valued more by receivers than by givers. This seeming paradox may be partly reconciled by demonstrating that the nature of asymmetry in favor evaluations depends on the timing of the evaluation. This idea was tested using a sample of experimentally constructed favors and a sample of actual favors performed by employees of an organization. In both studies, the evidence showed that favors were initially valued more by receivers than by givers following an episode of favor exchange. However, givers increased their favor evaluations and receivers decreased their favor evaluations as time passed, which suggests that egocentric biases may emerge over time.