In this article we are going to describe the development of a multi-agent system based on the JADE platform. This system is integrated in the COLLABORATOR European project which aims to provide a set of services to facilitate collaborative work among users. These users, the applications and the documents they share define the key concept of collaborative session. The multi-agent system helps the users to create and manage these sessions. The services provided by this multi-agent system are a distributed meeting scheduler and a personal agenda manager.