In this paper, we describe a technique for integrating heterogeneous information systems using concept bases. A concept base is build on top of each system to integrate, in order to semantically enrich its description. Each concept is described at three different levels: terminological definition, formal characterization, and representation in the underlying system. The different concept bases are then used to compare the concepts represented in the different systems and to establish correspondences between them in order to facilitate communication, cooperation, or integration. Our approach relies on results of the ConcepTerm project, dedicated to the study of concept dictionary building methodology and process. We also show that the building of a concept base can benefit database design and high-level interface definitions.