The issue of medication nonadherence has generated significant interest because of its complexity from both cost and outcomes perspectives. Of the 3.2 billion prescriptions written annually in the United States, estimates indicate that half are not taken as prescribed, especially among patients with asymptomatic chronic conditions. The objective of this study was to assess whether a comprehensive wellness assessment (CWA) program helps improve medication adherence for oral diabetic medications, statins, and angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers (ACE/ARBs) in a Medicare Advantage (MA) plan diabetic population. The Centers for Medicare & Medicaid Services includes these medications among its triple-weighted measures. The researchers used a retrospective panel study employing administrative claims data and member month-level enrollment data for members who were newly diagnosed with diabetes since 2010, allowing for up to 5 years of follow-up. The treatment variable of interest was whether the enrollee had undergone a CWA in the 12 months prior to the study. Results for the full sample show that a CWA visit in the prior 12 months is significantly associated with increased adherence to statin medication (incidence rate ratio [IRR]: 1.022, t-test: 2.51) and oral diabetes medication (IRR: 1.032, t-test: 3.00), but it is not significantly associated with adherence to ACE/ARB medication (IRR: 1.009, t-test: 1.09). Results vary considerably in subsamples stratified by dual Medicare and Medicaid eligibility status, presence of certain chronic conditions, and age. CWAs are most beneficial when targeted toward dual-eligible members or members younger than 65. On the basis of these findings, improving medication adherence by targeting CWA visits to certain MA member subcategories may be more cost-effective than using CWAs for the full MA membership.