Bilingual education refers to the use of two languages to teach academic subjects. It differs from world language education (formerly or elsewhere known as foreign language education), which generally focuses on teaching the target language rather than academic subjects per se. Bilingual education has traditionally referred to programs for linguistic minority students (often identified as limited English proficient or LEP; or English Language Learners (ELLs) in more recent decades), with goals of developing proficiency in English while using the home languages. The two main types of bilingual education programs are transitional bilingual education (TBE) programs that typically use the primary language as a transition or bridge to learning English, whereas maintenance bilingual education (MBE) programs strive to more fully develop biliteracy (McField, 2014; NCES 2015; U.S. General Accounting Office 1987a). The overwhelming majority of bilingual education programs implemented in the United States have been transitional or TBE.