This article reports the findings of a study examining independent variables that contributed to the science, technology, engineering, and mathematics (STEM) achievement of students with reading difficulties who participated in a technology-enhanced astronomy curriculum. The curriculum incorporated key elements of the Universal Design for Learning (UDL) theoretical framework. Participants (N = 1153) included middle school students from 64 inclusive science classrooms. A two-level hierarchical linear model was developed to determine the contribution of student- and teacher/classroom-level factors to the prediction of posttest and problem-solving scores. Results reveal differences across schools in the effect of being in a lower reading ability group on performance on the posttest and problem-solving measures, with some students performing at a level commensurate with their proficient reading peers. Factors associated with differential performance are identified. Implications of these findings are discussed. Areas for future research are identified. (Contains 6 tables and 4 footnotes.)