This book presents an account of the NATO Advanced Study Institute on "Energy Transfer Processes in Condensed Matter", held in Erice, Italy, from June 16 to June 30, 1983. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the "Ettore Majorana" Centre for Scientific Culture. The objective of the Institute was to present a comprehensive treatment of the basic mechanisms by which electronic excitation energy, initially localized in a particular constituent or region of a condensed material, transfers itself to the other parts of the system. Energy transfer processes are important to such varied .fields as spectroscopy, lasers, phosphor technology, artificial solar energy conversion, and photobiology. This meeting was the first encounter of this sort entirely dedicated to this important topic. A total of 65 participants came from 47 laboratories and 16 nations (Belgium, Czechoslovakia, F.R. of Germany, France, Greece, India, Ireland, Israel, Italy, The Netherlands, Poland, Portugal, Switzerland, Turkey, United Kingdom, and the United States of A America). The secretaries of the course were: Ms. Aliki Karipidou for the scientific aspects and Mr. Massimo Minella for the admini- strative aspects of the meeting.