Epidemiological studies have identified osteoporosis as a disease of significant public health impact and have delineated numerous potential risk factors. Nevertheless, it has proven difficult to establish preventive strategies for several reasons. First, there has been no final agreement on the definition of osteoporosis, which has hampered efforts to characterize the magnitude of the problem as a whole. Secondly, as osteoporosis is a multifactorial chronic disorder, effective programs for risk assessment and intervention depend on the development of complex disease models. In summarizing the contributions of epidemiological studies to the current understanding of osteoporosis this review intends to outline the scientific background for the European Vertebral Osteoporosis Study (EVOS) and its successors.