Background: Adult immunization rates are below Healthy People 2020 targets. Our objective was to evaluate the effectiveness of a multicomponent intervention to improve adult immunization rates. Methods: This prospective interventional before-and-after non-randomized study was conducted through the American Academy of Family Physicians National Research Network with 43 primary care physicians from a large multi-specialty healthcare organization (multicomponent intervention group n = 23; comparator group n = 20) in the United States. The multicomponent intervention included provider reminders, quarterly provider-level performance reports, provider education, patient visual aid materials, and standing orders on adult pneumococcal, influenza, and zoster immunizations. We assessed individual and comparative provider-level vaccination rates and missed opportunities detailing concordance with targets established by Healthy People 2020 for pneumococcal, influenza, and zoster immunizations. Results: Vaccination rates increased after 12 months in intervention and comparator groups respectively for: a). influenza from 44.4 ± 16.7 to 51.3% ± 12.9% (by 6.9 percentage points, p = 0.001) and from 35.1 ± 19.1 to 41.3% ± 14.2%, (by 6.2 percentage points, p = 0.01); b). pneumococcal vaccinations in older adults from 62.8 ± 17.6 to 81.4% ± 16.6% (by 18.6 percentage points, for p < 0.0001) and from 55.9 ± 20.0 to 72.7% ± 18.4% (by 16.7 percentage points, p < 0.0001); and c). zoster from 37.1 ± 13.4 to 41.9% ± 13.1% (by 4.8 percentage points, p < 0.0001) and from 35.0 ± 18.7 to 42.3% ± 20.9% (7.3 percentage points, p = 0.001).