The Pediatric Symptom Checklist-17 (PSC-17) is a brief form of the Pediatric Symptom Checklist that is designed to screen for behavioral health problems in primary care settings. It has been proposed to have three subscales: externalizing, internalizing, and attention problems. In the context of developing a behavioral health screening program in an inner-city primary care practice, we evaluated the construct validity of the PSC-17. A total of 331 families with children between 4 and 12 years of age who were seen for well-child care during the study were invited to complete the PSC-17 and 320 families (96.5%) did so. A confirmatory factor analysis was performed and the Comparative Fit Index and root mean square error of approximation fit statistics were calculated to determine whether the data fit the proposed three-factor model. We found that although the PSC-17 contained three subscales, several items did not load predominantly on the subscale that they were proposed to measure. Specifically, although the five items on the internalizing subscale loaded only on this subscale, only four of the seven externalizing items loaded exclusively on the externalizing subscale, and only two of the five attention items loaded exclusively on the attention problems subscale. Clinicians using the PSC-17 in urban low-income communities should recognize that the externalizing and attention problems subscales of the PSC-17 may not be valid measures of these dimensions of child behavior in this population.