preschool children diagnosed with either global developmental delay (gdd) or developmental language impairment (dli) were reassessed during their early school years with standardized developmental (battelle developmental inventory [bdi]) and functional (vineland adaptive behavior scale [vabs]) outcome measures. of an original cohort of 99 children with gdd and 70 children with dli assessed and diagnosed at a mean age of 3 years 5 months (sd 1.1) and 3 years 7 months (sd 0.7) respectively, 48 children (34 [71%] males) with gdd and 43 children (36 [84%] males) with dli were reassessed at a mean age of 7 years 4 months (sd 0.9) and 7 years 5 months (sd 0.7) respectively. the overall total mean bdi score for children with gdd was 66.4 (sd 4.3) versus 71.9 (sd 8.2) for children with dli (p=0.002). on each subdomain of the bdi, except communication, mean scores for the gdd group were significantly lower than for the dli group (p<0.05). similarly, the vabs total score for the gdd group was significantly lower than for the dli group (p<0.001). for each subdomain of the vabs, the gdd group scored significantly lower than the dli group (p<0.001). the proportion of children falling below meaningful cut-offs on the outcome measures selected was significantly higher for those initially diagnosed with gdd. preschool diagnosis of either gdd or dli has later prognostic validity with regard to persisting developmental and functional deficits.