In Volume I: Biochemistry, Physiology and Diagnostics, international experts in endocrinology, bone biology, and human physiology take readers through the basic research of vitamin D. This impressive reference presents a comprehensive review of the multi-faceted actions of vitamin D relating both to skeletal and extra-skeletal action. Researchers from all areas of vitamin D will gain insight into how clinical observations and practices can feed back into the research cycle and will, therefore, be able to develop more targeted genomic, proteomic and metabolomic insights into the mechanisms of disease. Volume II: Health, Disease and Therapy authoritatively covers the evidence for new roles of vitamin D, ranging from organ transplantation to cancer, diabetes, inflammatory bowel disease, multiple sclerosis, and renal disease. The coverage is appropriately broad, drawing on aspects of internal medicine, pediatrics, nutrition, orthopedics, oncology, neurology, obstetrics and gynecology, and immunology, as well as, new areas for vitamin D including liver metabolism, veterinary medicine and ICU care – including COVID-19. Clinical researchers will gain a strong understanding of the molecular basis for a particular disease and better understand future directions for research in this still-growing field.