Language immersion, or simply immersion, is a technique used in bilingual language education in which two languages are used for instruction in a variety of topics, including math, science, or social studies. The languages used for instruction are referred to as the L1 and the L2 for each student, with L1 being the student's native language and L2 being the second language to be acquired through immersion programs and techniques. There are different types of language immersion that depend on the age of the students, the classtime spent in L2, the subjects that are taught, and the level of participation by the speakers of L1.

In bilingual education, students are taught in two languages. It is distinct from learning a second language as a subject because both languages are used for instruction in different content areas like math, science, and history. The time spent in each language depends on the model. For example, some models focus on providing education in both languages throughout a student's entire education while others gradually transition to education in only one language. The ultimate goal of bilingual education is fluency and literacy in both languages through a variety of strategies such as translanguaging and recasting.