This longitudinal retrospective cohort study evaluated implementation of an intervention to improve management of osteoporosis after a fracture in a nonprofit group-model health maintenance organization (HMO) in the U.S. Pacific Northwest with 480,000 members and electronic medical record data. Participants were female HMO members aged 67 and older who sustained a qualifying clinical fracture(s) and who had not received a bone mineral density (BMD) measurement or osteoporosis treatment in the 12 months before the fracture (N=3,588). Phase 1 included outreach to clinicians and patients; Phase 2 added clinician and staff incentives. Primary outcome was “osteoporosis management”—receipt of a BMD measurement or osteoporosis medication in the 6 months after an index fracture. Before the intervention, 13.4% (95% confidence interval (CI)=12.0–14.8%) of patients had received osteoporosis management, and the time trend was not significant. Postintervention, the probability of osteoporosis management increased on average 3.1% (95% CI=2.6–3.5%) every 2 months throughout both study phases without a significant added improvement in Phase 2. Improvement varied according to clinic and was less likely for patients with dementia. Overall, the probability of osteoporosis management increased from the baseline level of 13.4% to 44.0% (95% CI=40.0–48.0%) by the end of the study period (20 months post-intervention). The study found that an outreach program to primary care providers and patients improved the management of osteoporosis after a fracture. If widely implemented, this intervention could substantially improve the secondary prevention of osteoporosis. More-individualized interventions may be necessary for high-risk subgroups.