The effectiveness of the Pediatric Symptom Checklist (PSC) as a psychosocial screening measure to meet Federal Medicaid/Early and Periodic Screening, Diagnosis, and Treatment (EPSDT) requirements was examined in 117 low-income preschool (aged 4-5 years old) Hispanic children during well-child examinations in three clinics over an 8-month period. The PSC identified 7% of the sample as at risk for psychosocial problems. The PSC was significantly associated with parental ratings of the children's problems in functioning, with pediatric clinicians' decisions to make mental health referrals, with degrees of associations similar to those found between PSC scores, and with the same measures with school-aged children in the same clinics. Cronbach's alpha was high (r = .87) and virtually identical in English, Spanish, oral, and written formats. Although it identified a slightly lower rate of psychosocial problems in 4-5-year-olds than it had in school-aged children, the PSC appeared to provide an effective method of screening for psychosocial problems during EPSDT examinations.