This volume contains selected papers presented at the 12th International C- ference on Conceptual Structures, ICCS 2004, held in Huntsville Alabama, July 19 23, 2004. The main theme of the conference, Conceptual Structures at Work, was chosen to express our intention of applying conceptual structures for hum- centered practical purposes. That invites us to develop not only clear conceptual theories, butalsomethodstosupporthumansintheapplicationofthesetheories in their societies. Some promising steps in this direction are being taken, but the gap between the researchers working on a highly sophisticated level on one side and the practitioners in many ?elds of applications on the other side is usually di?culttobridge.Someofushaveexperiencesinsuchpracticalcooperation, but we need more members of our community to be engaged in real life problems . We all know that solutions of complex problems in practice require not only a well-developed formal theory, but also an understanding of the whole context of the given problems. To support our understanding we need general philo- phical methods as well as formal theories for the representation of fundamental structures in practice. We believe that our community has powerful tools and methodsforsuccessfulapplicationsinpractice, butthatwemustdevelopaforum to present our results to a broader audience. First we must understand the s- ni?cant developments in our own group, which has activities in many directions of research."

This book constitutes the refereed proceedings of the 9th International Conference on Conceptual Structures, ICCS 2001, held in Stanford, CA, USA in July/August 2001.The 26 revised full papers presented were carefully reviewed and selected for inclusion in the proceedings. The book offers topical sections on language and knowledge structures, logical and mathematical foundations of conceptual structures, conceptual structures for data and knowledge bases, conceptual structures and meta-data, and algorithms and systems.