This book has evolved from our deep interest and involvement in the development and application of reliability evaluation techniques. Its scope is not limited to anyone engineering discipline as the concepts and basic techniques for reliability evaluation have no disciplinary boundaries and are applicable in most, if not all, engineering applications. We firmly believe that reliability evaluation is an important and integral feature of the planning, design and operation of all engineering systems; from the smallest and most simple to the largest and most complex. Also, we believe that all engineers involved with such systems should be aware of, and appreciate, not only the benefits which can accrue from reliability assessment, but also how such assessments can be made. Our primary objective has been to compile a book which provides practising engineers and engineering graduates who have little or no background in probability theory or statistics, with the concepts and basic techniques for evaluating the reliability of engineering systems. It is hoped that the material presented will enable them to reach quickly a level of self-confidence which will permit them to assimilate, understand and appreciate the more detailed applications and additional material which is available in the journals and publications associated with their own discipline.