The appearance of wireless networks and mobile computing requires building context-aware information systems. These systems are more and more based on the usage of Web Services, which are designed to support interoperable application-to-application interaction over the Web. Our aim is to build an Adaptive Web Information System based on Web services. Our contribution aims at proposing a new architecture of Web Information Systems, supporting the adaptation process to the user context and returning to the user a list of Web services adapted to his context. This architecture is based on an extension of AHA! architecture adding an adaptation layer containing various components dedicated to the context adaptation.