Lactose is the main carbohydrate in the milk of dairy animals; it is also the only dairy carbohydrate that is digested in the human small intestine. While lactose is digested by all human infants, it is conditionally digestible in human adults and its nutritional properties depend on the genetic background of the individual, the capacity of intestinal microbiota to ferment lactose without adverse effects for the host, and the presence of other components of the diet. In addition to lactose, milk of dairy animals contains glycoproteins and a low concentration free oligosaccharides. These dairy carbohydrates are indigestible but have multiple biological activities related to infant nutrition, the modulation of the composition and activity of intestinal microbiota, and the inhibition of pathogen or toxin adhesion to intestinal epithelia. This chapter provides an overview on carbohydrates and glycoproteins in milk, focusing on bovine milk, and their nutritional properties and biological activity.