U.S. education has experienced a push and pull regarding the language of instruction for Multilingual Learners (MLs), as evidenced by the 1998 passage of the “English-only law” with Proposition 227 in California in 1998 and its subsequent repeal with Proposition 58 in 2016. The idea that one language must be learned fully (or not at all) before a second language (English) can be introduced has led many schools to either teach native Spanish speakers exclusively in Spanish during early primary education or adhere entirely to English instruction without fully leveraging appropriate instructional practices for language acquisition.

However, learning language is not an either/or endeavor: As discussed in this paper, key research has established that the human brain can learn to read, write, and speak in two or more languages at the same time. In fact, MLs show increased metacognitive and metalinguistic skills along with strengthened executive function, which includes the skills of attention switching, cognitive flexibility, and working memory.

Even when English is the language of instruction and content-area mastery or skilled reading is the educational target, MLs can cultivate their heritage language assets. When effective instructional practices make the most of crosslinguistic transfer and integrated language instruction with ample spoken language practice, Structured Literacy approaches can support MLs in becoming proficiently multilingual and multiliterate. U.S. education has experienced a push and pull regarding the language of instruction for Multilingual Learners (MLs), as evidenced by the 1998 passage of the “English-only law” with Proposition 227 in California in 1998 and its subsequent repeal with Proposition 58 in 2016. The idea that one language must be learned fully (or not at all) before a second language (English) can be introduced has led many schools to either teach native Spanish speakers exclusively in Spanish during early primary education or adhere entirely to English instruction without fully leveraging appropriate instructional practices for language acquisition.