Validating the Power of Bilingual Schooling: Thirty-Two Years of Large-Scale, Longitudinal Research

ABSTRACT This chapter summarizes the findings of 32 years of research from all of our longitudinal studies to date, conducted in 36 school districts in 16 U.S. states, more than 7.5 million student records analyzed, following English learners (of all language backgrounds) as far as Grades K–12. These studies are very generalizable to all regions and contexts of the United States and have been replicated in other countries, answering questions regarding program effectiveness for policymakers in education. We have shown that English-only and transitional bilingual programs of short duration only close about half of the achievement gap between English learners and native English speakers, while high-quality, long-term bilingual programs close all of the gap after 5–6 years of schooling through the students’ first and second languages (L1 and L2). In addition, our studies answer the linguistic question of how long it takes student groups to reach grade-level achievement in their L2, and we have developed and refined our theoretical Prism model by collecting and analyzing program effectiveness data, basing the Prism model on our empirical findings.