The authors examined the effectiveness of a 2-year (kindergarten and first grade) oral English intervention provided to 534 Hispanic English-language learners in transitional bilingual education (TBE) and structured English immersion (SEI) programs. Using latent growth modeling, the authors compared instructional programs in relation to growth trajectories and rates in academic English oracy. The findings revealed that students in all four programs (treatment TBE, control TBE, treatment SEI, and control SEI) improved significantly (p less than 0.05) in a linear pattern over 2 years, and students receiving the intervention developed at a faster rate than those receiving typical instruction (p less than 0.05, effect sizes greater than 0.46). The authors concluded that (a) first-language instruction did not impede the learning of a second language, and (b) enhancements and best practices in TBE and SEI programs are needed to accelerate oral English acquisition to remove the initial disadvantage of low levels of English proficiency. (Contains 8 tables, 3 figures, and 2 notes.)