Traditionally, students with special educational needs, such as students with disabilities, were taught separately from students in general education. As legislation has driven the integration of these students into general education classrooms, approaches to inclusive teaching that seek to meet the individual needs of every student have come to the fore in education. The Universal Design for Learning (UDL) framework is one such integrative approach. The purpose of this quantitative causal comparative study is to examine what, if any, significant difference exists between UDL schools and non UDL schools in terms of average scores on the California Assessment of Student Performance and Progress (CAASPP) state 11th grade English and Math exam scores in LA County. Data were drawn from public records regarding 11th grade standardized test scores in reading and mathematics. These data were analyzed using Mann-Whitney U tests to compare 11th grade 2019 UDL and non-UDL school CAASPP scores in Math and English. The results of the Mann-Whitney U test for English CAASPP scores for UDL (M = 2635.03) and non-UDL (M = 2480.62) were U = 7065.00, p < 0.001, [eta squared] = 0.76. The results of the Mann- Whitney U test for Math CAASPP scores for UDL (M = 2649.42) and non-UDL (M = 2540.03) were U = 7569.00, p < 0.001, [eta squared] = 0.74. The results demonstrate that 11th graders in UDL schools outperformed 11th graders in non-UDL schools on the CAASPP English and Math tests in 2019 in LA County. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]