This book is the third volume of Advanced Dairy Chemistry, which should be regarded as the second edition of Developments in Dairy Chemistry. Volume 1 of the series, Milk Proteins, was published in 1992 and Volume 2, Milk Lipids, in 1994. Volume 3, on lactose, water, salts and vitamins, essentially updates Volume 3 of Developments in Dairy Chemistry but with some important changes. Five of the eleven chapters are devoted to lactose (its physico-chemical properties, chemical modification, enzymatic modification and nutritional aspects), two chapters are devoted to milk salts (physico-chemical and nutritional aspects), one to vitamins and one to overview the flavour of dairy products. Two topics covered in the first editions (enzymes and other biologically active proteins) were transferred to Volume 1 of Advanced Dairy Chemistry and two new topics (water and physico- chemical properties of milk) have been introduced. Although the constituents covered in this volume are commercially less important than proteins and lipids covered in Volumes 1 and 2, they are critically important from a nutritional viewpoint, especially vitamins and minerals, and to the quality and stability of milk and dairy products, especially flavour, milk salts and water. Lactose, the principal constituent of the solids of bovine milk, has long been regarded as essentially worthless and in many cases problematic from the nutritional and techno- logical viewpoints; however, recent research has created several new possi- bilities for the utilization of lactose.