Designing for user experience is central to good web design, particularly in e-commerce settings. However, the relevant dimensions and processes of designing for user experience have been variously defined. This project develops an approach to web design that defines the key dimensions of user experience, including interactivity, participation, and flow, and web site design of the user experience. The idea of Interactive User Experience Design is advanced as a model for designing from the perspective of user experience. The project reviews relevant dimensions of user experience, proposes a model integrating key design dimensions of this experience, surveys design literate university students on effective online experiences, and develops a prototype for a hypothetical commercial web site that incorporates elements of co-creation and identity play. This practice-based project contributes a new proposal for web-based design and new knowledge in the form of an approach to user experience design.