For those who have any doubts on the efficacy of bilingual education, below is a summary of the evidence from over more than 20 years.  I will follow up with my summary of why it works in a future blog.

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National Literacy Panel on Language-Minority Children and Youth (U.S.), August, D., & Shanahan, T. (2006). Executive summary: Developing literacy in second-language learners: Report of the national literacy panel on language minority children and youth. Mahwah, N.J.: Lawrence Erlbaum Associates. [meta-analysis]

“The research indicates that instructional programs work when they provide opportunities for students to develop proficiency in their first language. Studies that compare bilingual instruction with English-only instruction demonstrate that language-minority students instructed in their native language as well as in English perform better, on average, on measures of English reading proficiency than language-minority students instructed only in English. This is the case at both the elementary and secondary levels” (p.11).

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Rolstad, K., Mahoney, K., & Glass, G. V. (2005). The big picture: A meta-analysis of program effectiveness research on English language learners. Educational Policy, 19(4), 572-594. [meta analysis]

“Empirical evidence considered here indicates that bilingual education is more beneficial for ELL [English language learner] students than all-English approaches such as ESL [English as a second language] and SI [Structured immersion]. Moreover, students in long-term DBE [Developmental bilingual education] programs performed better than students in short-term TBE [transitional bilingual education] programs.”  (p.19)

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Kellie R., Mahoney K. & Glass, G. (2005)  Weighing the evidence: A metat-analysis of bilingual education in Arizona. Bilingual Research Journal. 29(1)

Abstract: This article reviews the current policy context in the state of Arizona for program options for English language learners and produces a meta-analysis of studies on the effectiveness of bilingual education that have been conducted in the state in or after 1985. The study presents an analysis of a sample of evaluation studies (N = 4), which demonstrates a positive effect for bilingual education on all measures, both in English and the native language of English language learners, when compared to English-only instructional alternatives. We conclude that current state policy is at odds with the best synthesis of the empirical evidence, and we recommend that current policy mandating English-only and forbidding bilingual education be abandoned in favor of program choices made at the level of the local community.

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Hofstetter, C. H. (2004). Effects of a transitional bilingual education program: Findings, issues, and next steps. Bilingual Research Journal, 28(3), 355-377. [primary research]

“After 4 years in their respective programs, students in ALA [Academic Language Acquisition, a form of transitional bilingual education] and SEI [Structured English Immersion] classes displayed only nominal differences, at best, in their performance on various achievement indicators. ALA and SEI students… were comparable on English-language SAT–9 tests in reading, mathematics, and language arts, as well as the reading and listening and speaking portions of the CELDT, an English-proficiency test. The only significant difference among groups occurred in writing, where students in… ALA … scored lower than their peers.” (p.16)

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Howard, E. R., Sugarman, J., & Christian, D. (2003). Trends in two-way immersion education: A review of the literature (Report No. 63): Center for Applied Linguistics. [research summary]

“On aggregate, the research summarized in this section indicates that both native Spanish speakers and native English speakers in TWI [two-way immersion] programs perform as well or better than their peers educated in other types of programs, both on English standardized achievement tests and Spanish standardized achievement tests.” (p.30)

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Thomas, W., & Collier, V. (2002). Executive summary: A national study of school effectiveness for language minority students’ long-term academic achievement. Washington, DC: Center for Research on Education, Diversity & Excellence. [primary research]

“Enrichment 90-10 and 50-50 one-way and two-way developmental bilingual education (DBE) programs (or dual language, bilingual immersion) are the only programs we have found to date that assist students to fully reach the 50^th percentile in both L1 and L2 in all subjects and to maintain that level of high achievement, or reach even higher levels through the end of schooling. The fewest dropouts come from these programs.” (p.7)

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Snow, C., Burns, S., & Griffin, P. (1998). Preventing reading difficulties in young children [electronic version] . Washington, DC: National Academy Press. Retrieved  March 24, 2007 from http://bob.nap.edu/html/prdyc/index.html [Research summary]

“The accumulated wisdom of research in the field of bilingualism and literacy tends to converge on the conclusion that initial literacy instruction in a second language … carries with it a higher risk of reading problems and of lower ultimate literacy attainment than initial literacy instruction in a first language.”

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Greene, J. (1997). A meta-analysis of the Rossell and Baker review of bilingual education research. Bilingual Research Journal, 21(2-3), 103-122.

“Despite the relatively small number of studies, the strength and consistency of these results, especially from the highest quality randomized experiments, increases confidence in the conclusion that bilingual programs are effective at increasing standardized test scores measured in English.”

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Thomas, W., & Collier, V. (1997). School effectiveness for language minority students. Washington, DC: National Clearinghouse for Bilingual Education. [primary research]

The first predictor of long-term school success is cognitively complex on-grade-level academic instruction through students’ first language for as long as possible (at least through Grade 5 or 6) and cognitively complex on-grade-level academic instruction through the second language (English) for part of the school day, in each succeeding grade throughout students’ schooling…. The second predictor of long-term school success is the use of current approaches to teaching the academic curriculum through two languages.” (p.16)

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Ramirez, J. D. (1992). Executive summary: Longitudinal study of structured English immersion strategy, early-exit and late-exit transitional bilingual education programs for language-minority children. Bilingual Research Journal, 16, 1-62. [primary research]

“Providing substantial instruction in the child’s primary language does not impede the learning of English language or reading skills.” (p.44)

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Willig, A. C. (1985) A Meta-Analysis of Selected Studies on the Effectiveness of Bilingual Education. Review of Educational Research

“Meta analysis results were compared with a traditional review of bilingual education program effectiveness. When controlled for methodological inadequacies, participation in bilingual education programs consistently produced differences favoring bilingual education.”