This article examines international research on student outcomes in one-way, two-way, and indigenous language immersion education. We review research on first and second language competence and academic achievement in content areas (e.g., math) among both majority and minority language students. We also discuss the relationship between bilingualism and student outcomes and whether more exposure to the first or second language is associated with better outcomes. In addition, we highlight student background, methodological, and assessment issues and concerns, and suggest additional avenues of research on student outcomes.