In December 1979, the Food and Drug Administration's (FDA) Division of Metabolic and Endocrine Drug Products issued its Guidelines for the Clinical Evaluation of Drugs Used in the Treatment of Osteoporosis. The Guidance Document recommended study designs, patient populations for study, and techniques for evaluating skeletal mass and fracture frequency that were considered central to showing the efficacy and safety of drugs used to treat and prevent postmenopausal osteoporosis (PMO). In this paper, I discuss the evolution of the Osteoporosis Guidance as it relates to the pharmaceutical industry's efforts to develop effective and safe anti-osteoporosis drugs. Current regulatory policy on osteoporosis drugs and thoughts on the future direction of the Osteoporosis Guidance are also provided.