Many persons gave generously of their time in the preparation of the fifteenth edition of Public Health & Preventive Medicine. The scientific contributors were most responsive to comments and editorial suggestions, and many had colleagues, too numerous to mention, who skillfully gave of their time in facilitating manuscript preparation and in communicating with the section editors and the editorial office. Particular appreciation is noted for Julie Bobitt, Linsey Abbott, and Nicole Schmidt who provided high-quality logistical and editing support for assembling the many contributions to this volume. Michael Brown and Maya Barahona of the McGraw-Hill Publishing Company also gave invaluable support, advice, and assistance in the assembly of this book. Finally, John M. Last, editor emeritus and the immediate past editor of the volume, has continued to provide skilled and welcome support for its content.