Syntes: Slavin et al. (2011) — the randomised trial that found bilingual-programme children behind in English reading in first grade, level by fourth

Källa: Slavin, R. E., Madden, N., Calderón, M., Chamberlain, A. & Hennessy, M. (2011). Reading and Language Outcomes of a Multiyear Randomized Evaluation of Transitional Bilingual Education. Educational Evaluation and Policy Analysis 33(1), 47–58. https://doi.org/10.3102/0162373711398127

Verified content

• [abstract] Spanish-dominant children were randomly assigned from kindergarten to transitional bilingual education or structured English immersion, for up to 5 years.
• [abstract] In first grade, the bilingual group scored significantly better in Spanish and significantly worse in English (vocabulary and Woodcock reading scales).
• [abstract] The differences shrank in grades 2 and 3; by grade 4, after the bilingual group had moved to English-only teaching, there were no significant differences on English reading.

• [abstract] The authors conclude that the quality of instruction matters more than the language of instruction.

• [full text, 2010 report] Six Success for All schools (Los Angeles, Denver, Albuquerque, St. Paul, Rockford, Alamo); three kindergarten cohorts (2004–2006) randomised within schools; Spanish-dominant children only; both arms got the same Success for All reading programme (Spanish or English version), so the language of instruction was the only difference; analyses controlled for PPVT and TVIP pretests.

• [full text, 2010 report] English reading (three Woodcock scales): bilingual group behind by an average effect size of −0.54 in kindergarten and −0.42 in grade 1 (significant on all English measures). After transition: −0.20 (grade 2), −0.16 (grade 3), −0.25 (grade 4), directionally favouring English immersion but significant in only one of nine comparisons (grade-2 Word Attack). English vocabulary (PPVT) stayed significantly lower in grades 2–4.
• [full text, 2010 report] Spanish reading favoured the bilingual group (+0.57, +0.63, +0.57, +0.44 in K–3; +0.34 in grade 4, significant only on Passage Comprehension).
• [WWC study page 67297] Sample sizes in the What Works Clearinghouse review: 148 (K), 247 (grade 1), 232 (grade 2), 207 (grade 3), 115 (grade 4).

Limits

• [assessment] Numbers are from the January 2010 report version (full text); the published 2011 article (8 tables) is paywalled and may differ slightly. Grade-4 sample is small (115), so a remaining −0.25 gap could be missed. One programme model (TBE vs SEI) in the US, Spanish-speaking children.
• [assessment] The early English gap is the sharpest test on file of C34's "do not lower reading by any reliable amount": the claim holds at the end, but not in the early grades.

Why it is in the library

The only multiyear randomised trial of bilingual versus English-only reading teaching we know of, and the study most often cited against strong pro-bilingual readings. The library had only meta-analyses for C34.

Added 2026-11-01 by the project (weekly source sweep, kind: old; read: abstract). Full text of the 2010 report read in the 2026-11-01 nightly attacks; applied to C34 (weakened). [abstract] = from the published abstract; [full text] = read in the full text; [assessment] = the project's own assessment.