This volume contains the complete proceedings of a NATO Advanced Study Institute on various aspects of the reliability of electronic and other systems. The aim of the Insti~ute was to bring together specialists in this subject. An important outcome of this Conference, as many of the delegates have pointed out to me, was complementing theoretical concepts and practical applications in both software and hardware. The reader will find papers on the mathematical background, on reliability problems in establishments where system failure may be hazardous, on reliability assessment in mechanical...