Social skills and academic competence are key factors influencing children's development and functioning across early childhood and through adolescence. There is a great need to understand the longitudinal patterns of growth in social and academic skills in order to further inform intervention, particularly for at-risk groups such as individuals with intellectual disability (ID). Using a sample of 204 children with (N = 84) and without (N = 120) intellectual disability, the present study utilized structural equation modeling techniques to examine the longitudinal development of social skills from age 6 to age 13. Latent growth curve analysis was used to model intraindividual and interindividual changes in social skills over time. The best fitting growth model specified a linear slope, or rate of change in social skills across time, which was greater for children placed in special education at age 6. Other covariates indicating risk-status at age 6 (ID status, special education placement, elevated externalizing behavior problems, and elevated internalizing behavior problems) significantly influenced children's initial social skills scores at age 6, accounting for additional variance in the growth model. In addition, the data were fit to a cross-lagged panel to model the relationship of social skills with academic competence over time. The academic competence-driven model fit the data better than the fully transactional and the social skills-driven models, supporting the importance of earlier academic competence to future social skills and academic competence. Furthermore, the predictive validity of parent and teacher ratings of age six social and academic competence was examined via multivariate regression analyses in relation to youth self-reports of competence at age 15. Teacher-rated age 6 academic competence, but not parent- and teacher-rated age 6 social skills, significantly predicted youth-reported competence at age 15. However, the mean of parent- and teacher-rated age 6 social skills did significantly predict youth-reported competence at age 15. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]