The purpose of this quantitative ex post facto study was to examine the differences that exist in academic outcomes between mobile and non-mobile middle-school students at a school district in Northeastern New Jersey. Students are considered mobile if they voluntarily change schools, whereas non-mobile students do not experience such transitions. The study included an analysis of the academic results and school mobility within the school year (2018-2019). Bronfenbrenner's Ecological Systems Theory established a relationship between a student's school experience and individual development. Both research questions analyzed the relationship between the independent variable of school mobility and the dependent variables for the academic outcomes of English Language Arts and Math. The sample consisted of 1,862 participants (116 mobile students and 1,746 non-mobile students). The results for English Language Arts were reported as t(1,846) = 5.140, p < 0.001. The results are statistically significant, in which nonmobile students (M = 734.99, SD = 42.394) scored higher on English Language Arts tests than mobile students (M = 713.64, SD = 40.050). The results for Math were reported as t(1,846) = 3.175, p < 0.001. The results are statistically significant, in which non-mobile students (M = 726.67, SD = 35.691) scored higher on Math tests than mobile students (M = 715.77, SD = 22.814). The findings contribute to education, indicating that nonmobile students achieve higher academic results than mobile students. [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.]