A literature review of existing assessment frameworks for B2C websites over more than ten years reveals that they are all built bottom-up through an essentially empirical approach of recording functionalities/features without any theoretical construct to guide the design of the framework. In an attempt to develop a theoretically consistent framework, this paper first identifies all relevant assessment categories and sub-categories for B2C websites in the luxury fashion industry. In total, eight categories and 29 sub-categories (actual assessment criteria) are identified. This framework is then applied to 15 luxury fashion brands in a longitudinal study in the years of 2006, 2008, 2010 and 2012. These four surveys document the substantial changes in website functionalities/features over the period, especially relating to how Web 2.0 and social media are diffused and adopted in the luxury fashion industry. A careful analysis of the eight categories and sub-categories reveals that the B2C website design can be characterized (and indeed defined) by virtue of three strategic choices regarding website design. The three strategic choices together with the eight categories form the basis for a theory for website design, which we name the CUBE model. We believe this model to be relevant beyond the luxury/fashion industry.