In order to develop the optimal mix of online and offline services for a particular product, marketers must determine which key attributes are perceived by their target market to be delivered better online or offline. A multi-part survey was administered to assess how product attribute evaluations drive differences in online/offline shopping preferences between products, between consumers, and between stages of the shopping experience. Two groups of participants - a student sample and a sample from a national survey panel - were asked to rate their likelihood of shopping online or offline for each of a series of products, both at the search stage and at the purchase stage. They were then asked to rate the importance of attributes that might have differential importance for products like clothing and books, and to rate the extent to which they thought each attribute was delivered better online or offline. For both samples, differences in importance weights assigned to attributes that favor online shopping and attributes that favor offline shopping were key predictors of observed differences in shopping mode preference across products and across consumers.