Digital computers have been used more and more to control different industrial processes during the last decade. As of today, many sy­ stems are designed to include a process control computer as a vital part. The use of computers has created a need for sophisticated me­ thods for the operation and supervision of complex industrial proces­ ses. To summarize the state of the art from the practical as well as from the theoretical point of view, the 4th IFAC/IFIP International Conference on "Digital Computer Applications to Process Control" will be held at Zurich from March 19 to 22, 1974. The first two vo­ lumes of the proceedings contain the accepted papers submitted to the conference mentioned above. The papers are arranged according to the topics of the conference. A third volume will include the six follow­ ing survey papers: 1. Digital Control Algorithms Prof. A. P. Sage, Dallas Texas / USA 2. Interface Problems for Process Control Prof. T. J. Williams, Lafayette Indiana / USA 3. Software for Process Computers Dr. J. Gertler, Budapest / Hungary Dr. J. Sedlak, Prague / CSSR 4. Digital Computer Applications in Metallurgical Processes Mr. W. E. Miller, Salem / USA Mr. W. G. Wright, Schenectady / USA 5. Digital Computer Applications in Power Systems Mr. D. Ernst, Erlangen / FRG 6. Digital Computer Applications in Chemical and Oil Industries Dr. H. Amrehn, Marl / FRG We hope, that the publication of these papers from specialists.