Design tools can be profitably associated with libraries of reusable modeling components that will make the description and also the validation of the models much easier. Furthermore, applications of today and tomorrow will be increasingly based on three fundamental technologies: Object Orientation, Client/Server and Internet. We propose in this article an object-oriented architecture for the definition of Web-based hierarchical models libraries. The originality of our approach lies in the facts that it is based on : (i) a notion of genericity of use, (ii) notions like inheritance and abstraction links between the stored models and (iii) Webbased storing and consulting libraries procedures. Categories and Subject Descriptors J.6 [Computer Applications]: Computer-Aided Design; D.2.11 [Software]: Software Engineering--Software Architectures; D.2.13 [Software]: Software Engineering--Reusable Software General Terms Design, Management Keywords models reuse, models libraries, Web-based acce...