The previous editions of this book have been the preferred text and reference in biological gerontology. The second edition, published by Sinauer, has sold about 2700 copies, but the reviews have all been very positive. Here is a good, solid overview of a rapidly changing field, and it appropriately reflects the changes, the disputes, and the glut of new data. It introduces aging, defines it, describes the statistics and parameters that measure it, compares it in different species and models, and focuses the material back onto human aging and its clinical and demographic outcomes. This fresh edition builds on Arking's previous sound scholarship.