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