BACKGROUND Social determinants of health (SDH) play an important role in health outcomes. This study sought to evaluate the effectiveness of a SDH screening and health-related social needs (HRSNs) referral program in an emergency department (ED) setting with adult Medicaid beneficiaries. METHODS Between November 2016 and March 2017 we enrolled adult Medicaid patients in a prospective cohort study. Research assistants (RAs) completed an SDH screening survey with participants and asked them if they needed assistance with HRSNs related to medical, behavioral health, wellness, housing, food, legal and job training issues. RAs referred participants to community-based organizations (CBO) for their top three HRSNs. Patients referred to at least one CBO were phoned a month later to determine whether their HRSN was addressed and CBOs also reported their assistance rates within four months of the ED visit. RESULTS Of the 505 patients enrolled, 69% were female, 82% completed high school, and 57% reported working. Most participants (85%) requested assistance for at least one HRSN. Almost half (44%) received referrals to three different agencies. Help with housing (70%), medical issues (51%), and finding food (42%) were the most common. Among the 430 subjects referred to ≥1 agency, 76% completed the follow-up interview. Few patients reported receiving help from the referral agencies (5% for a wellness program to 15% for medical services). Referral agencies generally reported even lower assistance rates (0% for job training to 17% for medical services). CONCLUSIONS The majority of adult Medicaid patients treated in our ED wanted assistance with one or more HRSN. The passive referral system we implemented resulted in few patients receiving assistance from the referral agency, regardless of whether measured by self-report or by agency.