Information Systems that are accessible via the web have become a very important class of large-scale software systems. In order to assure a high quality of such systems we propose a layered approach using integrated methods for all levels. In doing so we bring together knowledge from semiotics, goal-oriented requirements engineering, conceptual modelling, databases, human-computer interaction and web-oriented languages. In this paper we outline our approach and argue why the systematic application of our methodology to web information systems development will result in quality.