The Fourth ECMI Conference on Industrial Mathematics took place at Strobl in Aus­ tria, May 29-June 2, 1989. The conference was devoted to the exchange of ideas, models and methods from various fields of industrial applications of mathematics. About 140 people from 21 countries attended the meeting. The aim was to bring together peo­ ple from industry and from university. In this respect the organizers were only partly successful!. The participance of about 20 people from industry shows that there is still much work to be done to increase the acceptance from this side. 72 speakers presented their results as invited or contributed lectures, or in the frame of 2 minisymposia. One minisymposium was organized by Heinz W. Engl and focused on steel processing, the other one, organized by Hansjorg Wacker, dealt with chemical engineering. These proceedings consist of 56 papers. The articles within each of the sections: Invited Lectures, Minisymposium Steel Processing, Minisymposium Chemical Engi­ neering, and Contributed Lectures are in alphabetical order of the first author. Exept for the contributions to the minisymposia, which clearly concentrate on the corre­ sponding topics, it is hard to find a reasonable classification of the papers . This, we believe, is typical for industrial mathematics and underlines the vast variety of fields where mathematics could be used to support problem solving. We would like to acknowlegde the valuable work of the referees of the articles who certainly helped to improve the quality of this volume.