More than 99% of European enterprises are SMEs. While collaboration with other enterprises provides potential for improving business performance, enterprise interoperability research is yet to produce results which can be used by SMEs without the need for high start-up costs (learning costs as well as system purchasing and installation costs). For a solution to be taken up by SMEs it must offer both "zero costs of entry" and "zero time for set-up" to the SMEs; its initial interaction with the system should follow familiar interaction patterns based on existing tools such as email or a web browser.Commius aims to deliver an adaptable and customisable software prototype, providing SMEs with "zero-cost of entry" into interoperability using the ideas behind the Interoperability Service Utility. This will be made possible by a number of innovative scientific, technical and business advances over the existing state-of-art.We will build such an interoperability solution for SMEs, allowing them to reuse existing and familiar applications for electronic communication. The solution will be downloaded with an SME's consent using automated self-installation routines. The solution will hook into their email infrastructure and collaboration systems such as Microsoft Exchange. It will then proceed to establish interoperability agreements with the peers of the SME at the levels of system, semantics and even process. Semantic analysis of actual enterprise data and documents¾used within and exchanged between pairs of SMEs¾will form a core part of this process. The consortium will validate results using 3 business cases: one business case comes from an technological district of SMEs; one from cross border interoperability and collaboration for European export; and one from inter-enterprise resource planning.