Despite benefits of the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC), many eligible children remain unenrolled. This study evaluated responses to an electronic health record (EHR)-embedded federal nutrition program (FNP) participation screening and WIC referral tool implemented within eight clinics during <5-year-well visits. Among 5,385 children, mean age at initial screening was 10.7 months (SD 14.2), 52% newborn-aged, 37% Hispanic, and 88% Medicaid-insured. Among screened patients (n=3,606), 34% were not enrolled in WIC at first screening (n=1,235). Medicaid coverage, academic clinic setting, and non-Hispanic Black or Hispanic race and ethnicity were associated with lower odds of WIC non-enrollment. Among those not enrolled with a documented response to referral (n=819), 59% accepted (n=488); acceptance was higher among non-Hispanic Black and Hispanic patients, newborn-aged patients, those with Medicaid coverage, and those seen in academic clinics. Among referral acceptors with follow-up (n=438), 61% were enrolled at last screening (n=265), with higher odds among newborn-aged patients and those in academic clinics. An EHR-based automated intervention can facilitate screening and referral to WIC. WIC participation at first screening, referral acceptance, and enrollment after referral varied by sociodemographic characteristics, suggesting opportunities to improve equitable access through health system-based approaches.