The purpose of this secondary analysis of state-collected data was to investigate developmental outcomes of preschool special education (PSE) services in a statewide cohort of participating children (n = 17,828). In line with federal performance indicators for Individuals with Disabilities Education Act early childhood programs, the outcome of interest in this study was the percentage of children who demonstrated age-expected functioning in all 5 major domains of development--communication, cognitive, motor, personal-social, and adaptive--at the time they exited the PSE program. The study also investigated the extent to which this outcome varied, depending on the severity and complexity of children's delays when they began PSE services. Overall, 38.2% of children exited the program within age norms in all 5 domains; percentages for subgroups of children ranged from 77% for children with no measured delay on entry to 23% for children demonstrating severe delay in 1 or more developmental areas. Holding delay severity constant, each additional domain of delay on entry was associated with a decrease in the percentage of children exiting within age norms. Findings of the study problematize the application of a single definition of "expected progress" for all participating children and underscore the utility of examining and reporting program outcomes for subgroups of children.