This book constitutes the refereed postworkshop proceedings of the Fourth Canadian Workshop on Information Theory, held in Lac Delage, Quebec, in May 1995.The book contains 18 revised full papers selected from 30 workshop presentations; also included are three invited contributions. The book is divided into sections on algebraic coding, cryptography and secure communications, decoding methods and techniques, coding and modulation for fading channels, and signal processing and pattern recognition.