The development of reading skills from age seven until age 19 was investigated for children who were referred for special education preschool intervention using latent growth curve analysis (n=206). Approximately one-third of the study sample did not require special education services after preschool, providing a natural comparison group. Reading achievement was conceptualized as the Simple View of Reading, where reading is assumed to be the product of decoding and comprehension. Since reading is a developmental process, it is theorized to grow at a non-linear rate, with large differences among individuals. Reading trajectories are apparently stable from an early age, thus predictors of individual trajectories can be hypothesized and their effects estimated. Latent growth curve models allow for intraindividual differences and can accommodate various growth trajectories. In addition, early predictors of reading trajectories for individuals who are at risk for reading difficulties can be added to the model.

Results indicate that there were large differences in intercept, or starting point of reading achievement for children who required special education services post-preschool intervention and children who did not. Although there were small but significant differences in growth over time, the trajectories of these two groups were remarkably similar. Both groups had negative trajectories that were quadratic in form, indicating that children who started higher experienced slower growth than children who started lower, and that they both lost ground in reading skills compared to same aged peers over time. In this sample, girls experienced lower achievement than boys, and children with lower SES (as measured by free and reduced lunch) experienced more growth than children with higher SES. The preschool verbal intelligence post-intervention scores of the children accounted for a moderate amount of variance in reading achievement outcomes.