For the first time, an entire publication has been dedicated to providing a critical review of the identification and analysis of the milk specific proteins such as lactalbumin, lactoferrin and casein; the non-milk specific proteins such as plasma and membrane proteins; and the minor nitrogen-containing components such as enzymes, hormones, and growth factors. Biological roles, whether nutritional, endocrinological or immunological, of the specific nitrogen compounds in mammary milk production and/or growth and development of the breast-fed infant are also presented. Identification of the molecular weight compounds that have led to questions about their function in milk and their inclusion in modern infant formulas is thoroughly discussed and of great value to scientists in sub-specialties of biochemistry, nutrition, physiology and immunology, as well as to pediatric practitioners with primary interests in the infant food industry, academia, or clinical nutrition. The thoroughness of each chapter, often providing an historical panorama of the specific aspect of milk composition, makes this book useful for both the uninitiated and expert audiences who are interested in advancing their knowledge of human milk biochemistry and its physiological significance to the recipient infant.