During the past decade, customers have become familiar with using various interface technologies, such as Web sites and wireless devices, to interact with firms. Increasingly, they choose the times and the channels through which they deal with firms for different aspects of their interactions. It is becoming common for customers to use different channels at different stages of their decision-and-shopping cycles, for example, using Web sites to obtain information but making purchases offline; in the past they typically obtained all their channel services from a single integrated channel at all stages of their decision process. We refer to customers who use more than one channel to interact with firms as multichannel customers, and marketing strategies to reach such customers as multichannel marketing. According to a study by Doubleclick (2004), the incidence of multichannel shopping among online shoppers increased from 56% to 65% between the 2002 and 2003 holiday seasons.