This book is a collection of selected papers presented at the symposium titled In situ Spectroscopy in Monomer and Polymer Synthesis, held at the April, 2001 ACS National Meeting in San Diego, California, USA. The co-organizers of this symposium were Timothy Long, Judit E. Puskas, Robson F. Storey, and J. Andrews. In situ spectroscopic monitoring is gaining popularity both in academia and industry. FfIR monitoring is used most frequently, but UV-visible, raman, and NMR spectroscopy are also important. This book concentrates mostly on FfIR monitoring, both in the near and mid-infrared ranges. The first chapter is a short general overview of FfIR spectroscopy, followed by the symposium contribu tions. We thought that this would be especially useful for student readers. We hope that the book will present a state-of-the-art overview of research related to in situ spectroscopic monitoring. -Judit E. Puskas ix Acknowledgments This book would not have been possible without the dedicated effort of the chapter contributors and the symposium committee: Professor Judit E. Puskas Professor Timothy Long Professor Robson F. Storey Professor J. Andrews The symposium was financially supported by: ACS-Petroleum Research Fund REMSPEC Co. Wyatt Technology Co.