This study evaluated rates of adherence to biologic DMARDS, measured by proportion of days covered (PDC), across 20 health-system specialty pharmacies through the Health-System Specialty Pharmacy Outcomes Research Consortium. The final median PDC after accounting for appropriate gaps in therapy was high at 95% (IQR, 0.87-0.99), demonstrating the benefits of health-system specialty pharmacies in helping patients with RA remain on effective therapies.