The study examined estimated effects of school mobility on students' academic and behaviouiral outcomes. Based on data for 2,560 public schools from the School Survey on Crime and Safety (SSOCS) 2007-2008, the findings indicate that high schools, urban schools, and schools serving a total student population of more than 50 percent minority students tend to have more school mobility than their counterparts. After controlling for safety initiatives, violence, and school background characteristics, school mobility is negatively associated with principals' perceptions of students' levels of aspiration and school achievement but positively associated with principals' perceptions of students' insubordination. The study offers policy implications for school administrators.