This study examines student mobility in California, particularly at the secondary level. It investigates the incidence, consequences, and causes of non-promotional school changes and offers strategies to address the issue. It also draws on an extensive dataset from various sources, including surveys and interviews with California students, parents, and schools. The findings highlight the negative impact of student mobility on educational achievement and suggest that families, schools, community agencies, and policymakers should take action to mitigate its harmful effects.