Osteoporosis is a major public health problem through its association with age-related fractures. Although fracture risk at any skeletal site depends upon a complex interaction between bone strength and trauma, recent epidemiologic studies confirm that bone density is currently the best single predictor of future fracture. The increasing burden of osteoporotic fractures urgently requires effective preventive strategies aimed at maximizing peak bone density, preventing excessive bone loss, and reducing the risk of falls.