This article reviews experimental studies comparing bilingual and English-only reading programs for English language learners. The review method is best-evidence synthesis, which uses a systematic literature search, quantification of outcomes as effect sizes, and extensive discussion of individual studies that meet inclusion standards. A total of 17 studies met the inclusion standards. Among 13 studies focusing on elementary reading for Spanish-dominant students, 9 favored bilingual approaches on English reading measures, and 4 found no differences, for a median effect size of +0.45. Weighted by sample size, an effect size of +0.33 was computed, which is significantly different from zero (p less than 0.05). One of two studies of heritage languages (French and Choctaw) and two secondary studies favored bilingual approaches. The review concludes that although the number of high-quality studies is small, existing evidence favors bilingual approaches, especially paired bilingual strategies that teach reading in the native language and English at different times each day. However, further research using longitudinal, randomized designs is needed to determine how best to ensure reading success for all English language learners. (Contains 1 table and 1 note.)