As prior empirical and conceptual work indicates, success and usability of web information systems is subject to navigational design. Although web information systems are not a new phenomenon and were examined intensively in the past, holistic in-depth investigations of navigational issues seem to be arbitrary rather than theoretically and conceptually founded. In particular, we argue that we are lacking an appropriate description language serving as a shared conceptualization of our subject of research. We present a conceptual framework for describing and assessing web information systems and their navigational capabilities. Moreover, we provide some empirical evidence of its applicability by reporting on a case study that pays special regard to navigational design and usability improvement.