The Pediatric Symptom Checklist (PSC) is a brief, well-validated parent-report questionnaire designed to detect psychosocial dysfunction in school-age children during pediatric primary care visits. This study assessed the utility of the PSC when completed by children (PSC-Y) ages 9-14 in a public school when parents are not available (n = 173). The PSC-Y identified 20% of children as having psychosocial problems, a rate similar to other low-income samples. When compared with teacher ratings of attention and behavior problems, the PSC-Y showed a sensitivity of 94% and a specificity of 88%. The PSC-Y correlated significantly with teacher and parent measures of child dysfunction, and with child-reported symptoms of depression and anxiety. Three quarters of the children identified by the PSC-Y were not identified by parents on the PSC. These children had impairment on all other measures, but fewer than one in five had received mental health services, suggesting the PSC-Y identified children with unmet mental health needs. The PSC-Y has the potential to be a rapid, easily administered tool for large-scale mental health screening in schools.