The general question of how well parents' reports about their preschool children predict school performance was addressed in this study. In addition, the effects of several population characteristics--sex, socioeconomic status (SES), child's age, and birth order--upon the validity of parent reports were investigated. Parents of 391 preschool children aged 49 to 64 months completed a brief developmental inventory as part of a preschool screening program operated by an urban school district. The 28-item developmental inventory assessed adaptive behavior and language development. In addition, preschool children were administered the Minneapolis Preschool Screening Instrument. Teacher ratings of kindergarten performance the following year provided criterion data to validate the screening measures. Correlations with the overall teacher rating (the mean of nine ratings) were .40 for the adaptive behavior scale and .57 for the language scale. Validity figures for the development inventory were significantly higher for low-SES than for high-SES children, for older children (57 to 64 months) than for younger children (49 to 56 months), and for firstborn children than for younger siblings. No effects were found by sex. While a positive relationship between parent reports of developmental functioning and early school performance was clearly established, validity levels did not justify use of parent information as a sole source of preschool screening information. (Author/MP)