Objective: This study evaluated the effects of a social determinants of health (SDH) screening tool and service referral on emergency department (ED) use among patients at a Federally Qualified Health Center primary care clinic. Study design: Quasi‐experimental. Sample: Three‐hundred and eleven English‐speaking patients 18 years and older. Measures: The Core 5 SDH screening tool consists of five yes/no items assessing food, housing, utilities, transportation, and safety needs. The number of ED visits 3 months before and after the intervention were collected from electronic health records. Intervention: The research team administered the Core 5 SDH screening tool and if desired, referred patients with an identified need for SDH services. Results: Approximately 43% of patients reported a SDH need with food insecurity most prevalent (62.2%). The number of ED visits was significantly lower 3 months post‐intervention compared to 3 months before for the 125 participants who wanted and received the SDH service referral (IRR = 0.64, 95% CI = 0.41, 0.99) and for the 35 participants who reported receiving some/all of the needed services at the 2‐week follow‐up (IRR = 0.36, 95% CI = 0.17, 0.76). Conclusions: Addressing patients' SDH needs may reduce ED visits, lower healthcare costs, and ultimately, improve health. [ABSTRACT FROM AUTHOR]