Previous literature suggests that academic achievement and self-concept among adolescents in the general education population are positively related (e.g., Huang, 2011). For students with disabilities, however, the correlation between academic achievement and self-concept is sometimes negative and non-significant (Daniel & King, 1995; Feiwell, 1997; Houck & Houck, 1976; Young, 1990). Limited research has investigated the relations between academic achievement and self-concept of students with disabilities and few studies consider this relation over time. This study design included four features to address the gaps in the literature: 1) methods appropriate for complex data sets; 2) use of latent constructs; and investigation of differences 3) between genders and 4) among the categories of disability. Three questions were investigated: What are the relations between self-concept and academic achievement over time among adolescent students with disabilities? What are the differences in these relations among male and female adolescents with disabilities? What are the differences in these relations among adolescent students with emotional disturbance (ED), intellectual disabilities (ID), and learning disabilities (LD)? In a secondary analysis of the Special Education Elementary Longitudinal Study (SEELS) database, cross-lagged longitudinal panel path analyses were used to explore the relations among the overall sample of 14-year-olds as well as of males-only, females-only, ED-only, ID-only, and LD-only subgroups. Additional procedures were used to account for issues due to missing data, non-normality of distributions, and clustered, stratified, and disproportionate sampling. Results of the study suggested that the relations between academic achievement and self-concept were complex. In the overall sample, no significant relations were found. When split by gender, the data indicated nearly equal but opposite path coefficients from self-concept at Time 1 to academic achievement at Time 2. The paths from academic achievement at Time 1 to self-concept at Time 2 obtained statistical significance among the ED-only (positive) and LD-only (negative) groups. The subgroup differences in the relations between academic achievement and self-concept suggested that more subgroup analyses need to occur. None of the study's hypotheses were fully supported by the data. The recommendations for practice, policy, and research are presented. [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.]