Current web site development is still dominated by technical issues. In order to enable efficient communication between developers and to provide a stable foundation for adopting new technologies, web sites should be derived from conceptual models. Based on the state-of-the-art of conceptual modeling as implemented in current CASE environments as well as web site development tools, the “essence” of a web site is identified, and an adequate conceptual meta model is proposed. Appropriate web site models are intended to capture not only hierarchical document structure and hypertext semantics, but also dynamical page generation from databases as well as explicit and implicit navigation. It becomes evident that web sites can be regarded as supersets of traditional information systems, thereby requiring conceptual modeling to include various additional features. The proposed meta model comprises several classes of information objects, various types of associations, design rules, and quality checks. For illustration purposes, the model is applied to an existing web site. Commercial web site development tools are analyzed with regard to the extent to which they support conceptual web site modeling.