Research demonstrates that student mobility, or students transferring schools, significantly affects student academic outcomes, making it a critical concern for policymakers and practitioners. Within-school-year transfers, in particular, often reflect sudden, unexpected circumstances. However, research on the prevalence, risk factors, and patterns of student mobility remains limited. This study leverages an ecological framework to identify student, school, and neighborhood characteristics linked to within-year school transfers and to examine whether these patterns differ across urban and suburban/rural contexts. Using regression modeling with Missouri state data spanning 15 years, we examined who moved and where students moved. The results reveal both expected and novel patterns, such as higher transfer rates among students with unstable housing and special education needs, as well as among students that attend high-suspension schools. These results have important implications for policy, practice, and future research.