As Congress considers two bills to support Native American language immersion, including the Native Language Immersion Student Achievement Act, it is time to take stock. What does research say about the impact of Native-language immersion on Native students’ academic achievement? We now have 30 years—more than a generation—of data on Native-language immersion in the U.S. and beyond. In this article I highlight key findings from this research.

But first, what do we mean by Native-language immersion? It may be easier to begin with what immersion is not. Native-language immersion is not simply “Native language instruction.” It is not a pullout program or a 50-minute class. Native-language immersion is not submersion, a method that compels students to learn a second language at the expense of their mother tongue.

Native-language immersion is voluntary; parents often participate in immersion themselves to support their children’s language learning at home. Native-language immersion is additive, building on students’ first-language abilities as a foundation for learning the Native language as a second language. Native-language immersion is full-day or most-of-the-day teaching and learning in the Native language, often complemented by after-school and summer programs. Native-language immersion systematically incorporates Native cultural content and culturally appropriate ways of teaching and learning. Most important, Native-language immersion not only engages students in learning the Native language, but also math, science, social studies, music, art, and even English through that language. In other words, Native-language immersion is a whole program that cultivates what language researcher Fred Genessee calls “the whole child, the whole curriculum, the whole community.”