Using product assortment to gain a sustainable differentiation is becoming increasingly difficult in the current retail environment and is likely to become even more challenging as the importance of location continues to decline and the share of Internet-based retailing increases. Recent research, however, suggests that product assortment can play a key role, not only in satisfying wants, but also in influencing buyer wants and preferences. This article reviews and synthesizes empirical evidence indicating that (a) retailers can use the assortment subset that buyers consider to enhance the likelihood that a purchase will be made and to affect the specific option selected, (b) the manner in which the set of considered options are presented also affects buyer preferences and purchase decisions, and, (c) the effects of the considered options and presentation format interact with other elements of the marketing mix such as sales promotions. The implications of these findings for retailers, including ethical aspects of influencing buyer preferences, are discussed.