The presence of contaminant flavonoids in vitamin C preparations from citrus fruits initially led Szent-Gyorgyi and his collaborators to suggest that a flavonoid compound, with biological activity for the prevention of capillary fragility, was vitamin P. Later re search, although not disproving biological activity, discontinued the use of the vitamin classification for these compounds. However, the ubiquitous distribution of flavonoids in living organisms, and the continued discovery of various activity in biological systems makes these compounds targets of wide ranging investigation. This volume is primarily based on a Symposium on Flavonoids and related com pounds held during the 212th National Meeting of the American Chemical Society held in Orlando, Florida on August 28-29, 1996 under the sponsorship of the Division of Agricul tural and Food Chemistry. While the book is not intended to be a comprehensive volume on flavonoid research, the papers provide various approaches to exploring the biological functions of flavonoids in plants and animals, their chemical modifications for enhanced activity, some analytical techniques, as well as their use in food classification. A signifi cant portion is devoted to medicinal implications of these compounds. The organizers would like to express their appreciation to Tropicana Products, Inc., Bradenton, Florida, Coca-Cola Foods Division, Plymouth, Florida and the American Chemical Society's Division of Agricultural and Food Chemistry for financial support. Of course, the book could not be produced without the authors, whose cooperation and pa tience is greatly appreciated.