Many transactions are now computer mediated, making it possible for sellers to condition their pricing on the history of interactions with individual consumers. This paper investigates conditions under which price conditioning will or will not be used. Our simplest model involves rational consumers with constant valuations for the good being sold and a monopoly seller who can commit to a pricing policy. In this framework, the seller will not find it profitable to condition pricing on past behavior. We consider various generalizations of this model, such as allowing the seller to offer enhanced services to previous customers, making the seller unable to commit to a pricing policy, and allowing competition in the marketplace. All of these generalizations have equilibria with price conditioning.