This book is the outgrowth of the COMETT II Course on Advanced Instru­ mentation, Data Interpretation, and Control of Biotechnological Processes organized by the Katholieke Universiteit Leuven and the Universiteit Gent, and held at Gent, Belgium, October 1994. The editors of the present volume were very fortunate to find all invited speakers prepared to write state-of-the-art expositions based on their lec­ tures. Special thanks are due to all of them. The result is an account of recent advances in instrumentation, data interpretation, and model based op­ timization and control of bioprocesses. For anyone interested in this emerg­ ing field, this text is of value and provides comprehensive reviews as well as new and important trends and directions for the future, motivated and illustrated by a wealth of applications. The typesetting of all this material represented a tremendous amount of work. I am most grateful to my wife, Myriam Uyttendaele, and to Kurt Gheys, who did most of the proof-reading. Their efforts have increased a lot the uniformity in style and presentation of the different manuscripts. Many thanks also to the co-editors, for their continued support. Kluwer Academic Publishers is gratefully acknowledged for publishing this book, thus contributing to the transfer of the latest research results into large scale industrial applications.