The preparation of Aging, Immunity, and Infection has been a labor of labor. When we began, there existed a huge literature-but manage able, we thought, given our years of experience in the area often referred to as immunogerontology. However, in the time that we have been at work, the new relevant literature has increased at a prodigious rate. The more we read and tried to assimilate, the farther we fell behind. In order to have any hope of completing a book on this rapidly evolving topic, we have been forced to become increasingly selective in covering new and re cent publications. We dare to hope that many read ers will find the book useful and only a few will dweIl on the inevitable inadequacies. We consider the book a work in progress, and welcome suggestions for future editions. Five chapters cover several aspects of infection and the decline of immunity with age. The first chapter Human Aging: Present and Future, is devoted to demographics and theories of senescence. Chap ter 2 outlines the gradual breakdown of resistance to infection in the aged individual. Chapters 3 and 4 cover changes in innate and acquired immunity. The final chapter, Nutrition, Longevity, and Integrity of the Immune System, discusses such provocative ideas as life-span exten sion and nutritional intervention for the delay of immunosenescence.