Since the U.S. Recession of 2008, more Mexicans are leaving than coming to the United States. Many Mexican families return to Mexico with their U.S.-born--or "American Mexican"--children and youth. Approximately 700,000 American Mexican children and youth are now living and attending K-12 schools throughout Mexico (Gandara & Jensen, 2021; Jacobo-Suarez, 2017; Jensen et al., 2017; Passel et al., 2012). They are part of a broader category of students who have educational experiences on both sides of the border often referred to as transnational students. Return migration to Mexico presents both challenges and opportunities that affect their adaptation to Mexican schools. Current research identifies that they are "largely invisible" and face myriad bureaucratic, pedagogical, linguistic, and cultural challenges (Hamann et al., 2010, p. 230; Jensen & Jacobo-Suarez, 2019; Zuniga & Hamann, 2013). Although research suggests these students may be at academic risk because of challenges related to their return migration, there is limited research on how they fare academically in Mexican schools. Some work addresses the effects of migration on school attendance and education attainment, but less is known about the effects of migration on academic achievement or other developmental outcomes (Giorguli et al., 2021; Jensen et al., 2018). The purpose of this study is to provide information for researchers, practitioners, and policymakers in both countries to enhance academic learning opportunities for American Mexican students. While it expands our current understanding of transnational students by providing information about how they are performing academically in Mexican schools. This includes insights about their (a) individual and family background characteristics, (b) school and community milieu, and (c) migratory context in relation to their math achievement. Employing an ecological framework and a structural equation modeling (SEM) approach with multilevel data, I analyze 2018 mathematics achievement and survey data of a nationally representative sample of sixth-grade students in Mexico (a) to determine how American Mexican sixth-grade students compare to their Mexican peers and transnational counterparts consisting of those who are born in Mexico and have studied in U.S. schools (i.e., Mexican returnees) in terms of math achievement; (b) to evaluate the effects of school and community variables and migration-related factors on their math achievement; and (c) to evaluate the extent to which effects of migration on math achievement are moderated by teaching and school climate. Descriptive results offer a new narrative about transnational students. Prior studies have raised questions about their academic well-being in Mexican schools, advancing the premise that they may be falling through the cracks and academically failing, particularly on the evidence of their challenges to integrate in Mexican schools related to return migration and higher grade retention rates compared to their Mexican peers. Key findings highlight that (a) while transnational students (i.e., American Mexican students and Mexican returnees) are largely invisible in Mexico's education system, their math achievement varies considerably with American Mexican sixth graders' mean performance close to the Mexican national average and Mexican returnees' performance almost one standard deviation below; (b) there are striking distinctions in their social, educational, and migratory milieu that may be providing different in-school and out-school experiences even though their challenges may overlap in some ways, and (c) there appears to be a durable math achievement disparity between transnational students across observed differences that is not explained by the privileged social class backgrounds of American Mexican students and other factors. [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.]