The need has arisen for a comprehensive handbook for engineers faced with problems of radiation shielding design. Although there are several excellent books on shielding, they either do not give enough consideration to the many practical design problems, or are limited to special aspects of the subject. Recognizing the universal need, the International Atomic Energy Agency decided to sponsor the publication ofthe present Engineering Compendium on Radiation Shield­ ing. At the first editorial discussions it was agreed that, if such a book were to be undertaken, it would be appropriate not only to create a useful design tool for the practising engineer but also to include well-referenced basic data for the research worker. Although trying to keep the book down to a reasonable size, the editors have aimed at a complete presentation of the subject, covering and linking both the tech­ nology and the science of shielding. Efforts to make terms and definitions consistent throughout have been only partially successful, owing to the continuing development of new ideas. However, inconsisten­ cies that could not be eliminated are identified whenever possible.