Lactose is a disaccharide which is the main carbohydrate present in the milk of most mammals, including humans. In this book, the authors present current research in the study of the structure, food industry applications and role in disorders of lactose. Topics include the microbial transformation of lactose and the potential of B-galactosidases for probiotic and prebiotic purposes; the evolution and spread of the dominant genetic trait responsible for continued adult digestion of lactose; whey lactose fermentation by kefir immobilized on agro-industrual wastes; the tableting properties of crystalline and amorphous lactoses and their application in the production of pharmaceutical compacts; and lactose and its influence in the diffusion of divalent metal chlorides.