PURPOSE: This research determined the psychometric quality of a criterion-referenced measure that was thought to measure preschoolers' print-concept knowledge (PCK). METHOD: This measure, titled the Preschool Word and Print Awareness (PWPA), was examined using the partial credit model (PCM) to determine its suitability for use by clinicians, educators, and researchers. The extent to which the PWPA differentiated estimates of PCK for at-risk populations on the basis of socioeconomic status (SES) and language ability was also studied. The sample population was one-hundred twenty-eight 3- to 5-year-old children who varied in SES (middle, low) and language ability (typical language, language impairment) as derived from several previous or ongoing studies of emergent literacy intervention. RESULTS: The PCM fit analyses showed good fit between the overall data and the PCM, indicating that the PWPA provided a valid estimate of the latent PCK trait. SES and language ability were significant predictors of PWPA scores when age was used as a covariate. These results showed the PWPA to be suitable for measuring preschoolers' PCK and to be sensitive to differences among children as a function of risk status. CLINICAL IMPLICATIONS: The results show the PWPA to be an appropriate instrument for clinical and educational use with preschool children.