A substantial proportion of patients screening positive for social risks either decline assistance or do not follow-up with offered resources. This study examined patient interest in and engagement with offered social care assistance among adults with poorly controlled diabetes at an academic medical center. Surveys (n=307) and purposively sampled follow-up interviews (n=40) were conducted 6 months after randomization to receive guided online self-navigation or in-person assistance to address unmet social needs. Integrated mixed methods (data collected in 2019-2021) explored the motivators, barriers, and preferences regarding the uptake of offered assistance. Results were analyzed in 2021 using descriptive statistics, rapid qualitative analysis, and joint display models. A total of 77% of people randomized to online self-navigation and 14% randomized to in-person assistance engaged with offered assistance. Motivators for engagement were similar across groups and included ease of use, anticipating assistance that could address 1 or more needs, and interest in learning more about available resources. Barriers to engagement included not needing or desiring assistance, participants perceiving that offered assistance was not relevant to their needs or that they would not qualify, competing priorities/forgetting, previous negative experiences or stigma, and technology or access challenges (online self-navigation group). Preferences around offered assistance that directly addressed barriers to uptake included changing messaging and framing around offered help and the ability to tailor modalities. There are key barriers to the use of social care assistance that may directly reflect the process by which individuals are screened and offered assistance. Strategies to increase uptake should be patient centered and ideally provide multiple options for type of assistance and mode of engagement.