The field of oxygen study is immense. No single work on the subject can be comprehensive, and this volume makes no such claim. Indeed, coverage here is selective and the selection is somewhat personal. However, the choice of topics is vast There are chapters on the history of oxygen, oxygen in the universe, the biochemistry of oxygen, and clinical uses of oxygen. An alternate title could have been, "Some things you always wanted to know about oxygen, but didn't know where to find them easily." Some information in this wide-ranging work can not be found elsewhere. This book is intended not only for specialists, but also for nonspecialists engaged in or curious about any field of oxygen study, particularly if they wish to know more about other fields of oxygen. Thus, those who are interested in oxygen and are historians, astronomers, chemists, geochemists, evolutionists, biochemists, physiolo gists, pathologists, or clinicians will find here much of extreme value. It is intended to be read and understood at the graduate or advanced undergraduate level. This volume is divided into four parts. The first constitutes the background for Parts II and III, and the last integrates the preceding material with an overall perspective on oxygen in living organisms.