This volume contains selected papers presented at the 12th International Conference 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 humancentered practical purposes. That invites us to develop not only clear conceptual theories, but also methods to support humans in the application of these theories 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 fields of applications on the other side is usually difficult to bridge. Some of us have experiences in such practical cooperation, but we need more members of our community to be engaged in "real life problems".