Antiresorptive drugs have become the mainstay for the prevention and treatment of osteoporosis. Members of this class include estrogen, the selective estrogen receptor modulator raloxifene, four bisphosphonates (alendronate, risedronate, ibandronate, and zoledronic acid), and the receptor activator of NF-kB ligand (RANKL) inhibitor denosumab.(1) In contrast to this plethora of antiresorptive compounds, the sole formationstimulating agent currently available is teriparatide.(1) Thus, although there is clearly a clinical need for the development of additional formation-stimulating drugs, it remains an open question as to whether the osteoporosis market has room for yet another antiresorptive compound. It is in this context that location and timing become critical for a new antiresorptive drug. In terms of location, does the new drug offer advantages with regards to the compartment-specific (ie, trabecular, endocortical, periosteal) effects of the drug? And in terms of timing, is the new drug coming to market when there are concerns (real or perceived) regarding the efficacy or safety of currently available alternatives? Given the costs of bringing a new drug to market, these are high-stakes questions for another antiresorptive drug for osteoporosis. In the current issue of JBMR, two articles from Merck Research Laboratories (2, 3) collectively address the question of location for the antiresorptive compound odanacatib (ODN), which is just entering this high-stakes arena and is currently in phase 3 trials. ODN is a selective and reversible inhibitor of cathepsin K (CatK), which is a lysosomal cysteine proteinase that is highly expressed in osteoclasts and is critical for bone resorption.(4) Both articles are based on analyses of a carefully conducted primate study in which ovariectomized Rhesus monkeys were treated with either vehicle, ODN 6mg/kg/d, or ODN 30mg/kg/d for 21 months and compared with intact animals; Masarachia and colleagues (2) report results at the lumbar spine and Cusick and colleagues (3) present the hip data.