This paper presents an approach and a toolset for exploiting the benefits of conceptual modeling in the quality evaluation tasks that take place both before the deployment and during the operational life of a Web application. The full version of the paper is available as a technical report at the address: http://www.elet.polimi.it/upload/fraterna/FLMM2004.pdf Categories and Subject Descriptors D.2.2 [Software Engineering]: Design Tools and Techniques? evolutionary prototyping, Computer-aided software engineering (CASE). D.2.4 [Software Engineering]: Software/Program Verification ? Validation. General Terms Design, Verification. Keywords Conceptual Modeling, Web Application Quality, Web Mining.