This issue of Endocrinology and Metabolism Clinics provides a comprehensive review of osteoporosis written by the world's leading experts. Topics include new mechanistic insights into pathophysiology; bisphosphonates; combination therapy; atypical fractures; non-BP anti resorbers; anabolic therapies; calcium; the impact of Vitamin D on bones; extraskeletal effects of Vitamin D; glucocorticoid osteoporosis; relation to anorexia nervosa, coeliac disease, and diabetes; and male osteoporosis.