The later developmental trajectory of young children diagnosed early with global developmental delay was determined. Using a prospective study, preschool children diagnosed with global developmental delay were systematically reassessed during the early school years with standardized developmental and functional outcome measures (Battelle Developmental Inventory and Vineland Adaptive Behavior Scale). Of an original cohort of 99 children assessed and diagnosed at a mean age of 3.4 +/- 1.1 years, 48 were reassessed at a mean age of 7.3 +/- 0.9 years. Group performance on the Battelle Developmental Inventory overall was 66.4 +/- 4.3 (mean 100 +/- 15). Between 75% and 100% of the cohort performed at least 1.5 SD below the normative mean on the individual domains of the Battelle Developmental Inventory. Similarly, the group mean on the Vineland Adaptive Behavior Scale overall was 63.5 +/- 20.8 (mean 100 +/- 15), with between 61% and 76% of the cohort scoring more than 1.5 SD below the mean on each of the domains. Univariate and multivariate analyses on potential predictor variables identified a lack of an underlying etiology as predictive of poorer performance on the Battelle Developmental Inventory fine motor and motor domains and increasing severity of initial delay as predictive of poorer performance on the Vineland Adaptive Behavior Scale communication domain and overall score. Similarly, maternal employment and paternal postsecondary education improved Vineland Adaptive Behavior Scale communication scores, whereas paternal postsecondary education alone predicted better socialization and total scores on the Vineland Adaptive Behavior Scale. Children with early global developmental delay demonstrate persistent and consistently poor performance across all developmental and functional domains. Few variables are apparent at intake to predict later performance.