Standard Medicare Part D prescription drug benefits include substantial and complex cost-sharing. Many beneficiaries also have functional limitations that could affect self-care capabilities, including managing medications, but also have varying levels of social support to help with these activities. We examined the associations between drug cost responses, functional limitations, and social support. We conducted telephone interviews in a stratified random sample of community-dwelling Medicare Advantage beneficiaries (N = 1,201, response rate = 70.0%). Participants reported their functional status (i.e., difficulty with activities of daily living) and social support (i.e., receiving help with medications). Drug cost responses included cost-reducing behaviors, cost-related non-adherence, and financial stress. We used multivariate logistic regression to assess associations among functional status, help with medications, and drug cost responses, adjusting for patient characteristics. Respondents with multiple limitations who did not receive help with their medications were more likely to report cost-related non-adherence (OR = 3.2, 95% CI: 1.2-8.5) and financial stress (OR = 2.4, 95% CI: 1.3-4.5) compared to subjects with fewer limitations and no help; however, those with multiple limitations and with medication help had similar odds of unfavorable cost responses as those with fewer limitations. The majority of beneficiaries with functional limitations did not receive help with medications. Support with medication management for beneficiaries who have functional limitations could improve adherence and outcomes.