We draw on research in human-computer interaction, information systems, environmental psychology, and marketing to develop and to test a model, which suggests that salient design characteristics of the web store (aesthetics and usability) influence the emotions of visitors to the store's site, which in turn affect their attitudes toward the store. A study examined the proposed model in two e-commerce domainsbookstores and apparel stores. The results, based on data collected from 327 participants, suggest that the effect of the design aspects on attitudes toward the store was partially mediated by affect. In addition, certain design aspects also affected attitudes directly. Specifically, effects of perceived aesthetic aspects of the online store were mainly mediated by affect. The influence of perceived usability was mainly direct and less mediated by affect. Both pleasure and arousal were associated with attitudes toward the store, with pleasure being the main mediator between store design and attitudes toward the store.