The papers in this volume represent most of the contributions to the Symposium on the Physics of Opto-Electronic Materials held at the General Motors Research Lab- oratories in Warren, Michigan, on October 4, 5 and 6, 1970. The purpose of this Symposium was to examine the current status of knowledge related to the controlled alteration of the optical properties of solids through exter- nally-applied agencies, with the aim of assessing possible future directions of scientific effort to achieve efficient, practical control of light. Since the advent of the laser, the scientific community has...