People’s fairness preferences are an important constraint for what constitutes an acceptable economic transaction, yet little is known about how these preferences are formed. In this paper, we provide clean evidence that contrast effects arising from previous transactions play an important role in shaping perceptions of fairness. Buyers used to high market prices, for example, are more likely to perceive high prices as fair than buyers used to low market prices. Our data further allows us to isolate the differential impact of pure observation vs. the experience of payoff-relevant outcomes. We propose two classes of models of path-dependent fairness preferences - either based on endogenous fairness reference points or based on shifts in salience - that can account for our data. Structural parameter estimates for both types of models imply a substantial deviation from classical fairness models that assume history-independent fairness preferences. Our results have implications for price discrimination, labor markets, and dynamic pricing.