How much and what kinds of classroom interaction best promote language and content learning in different immersion contexts? This article reviews trends and major concerns for classroom interaction research in three language immersion contexts: two-way immersion, one-way immersion, and indigenous language immersion. Much of the research in two-way immersion contexts has focused on issues of equity in interaction. Research in one-way immersion contexts has primarily attempted to understand what kinds of interaction are most effective for L2 development, and how to teach students to interact in these ways. Driven by the urgency that accompanies efforts at language and culture revitalization, indigenous immersion research centers on the role of culture and community norms in classroom interaction. Despite the fact that research in these three contexts has focused on rather different issues, the article draws cross-context conclusions, arguing that findings from these settings can and should inform each other.