Key PointsQuestionWhat were the initial implementation challenges and solutions for a Medicaid accountable care organization participating in the Massachusetts Flexible Services program to address food and housing insecurity?FindingsIn this mixed-methods qualitative evaluation, implementation challenges included administrative burden, COVID-19 factors that influenced screening for social needs, data tracking and sharing, and coordinating with community organizations. Adaptive solutions included administrative funding for hiring enrollment staff, bidirectional communication with community partners, new strategies to identify eligible patients, and raising clinician awareness of the Massachusetts Flexible Services program.MeaningFuture state and health systems’ programs to address health-related social needs may benefit from minimizing administrative burden, providing funding for enrollment staff and evaluation, and developing effective information-sharing platforms.