The purpose of the study was to examine the effects of transitional bilingual education (TBE) and structured English immersion (SEI) instructional models on the development of English language learners (ELLs). Instructional strategies and educational philosophies are always changing. One constant, however, is the achievement gap between ELLs and mainstream students continue to widen. Thus, it is imperative to identify effective instructional programs for educating ELLs, particularly in their English language development. This research adds to current knowledge in regard to effective educational programs for the growing number of ELLs. The elementary school in the study implements both TBE and SEI programs. This study examined English language development between students who have been in the TBE vs. SEI programs consecutively for 4 years, as measured by the California English Language Development Test (CELDT). Students' oral proficiency (listening and speaking) scores were collected in grades K-3 and student's' literacy proficiency (reading and writing) scores were collected in grades 2-3.

Using repeated measures MANOVA procedures, the study found that both programs continue to demonstrate growth in all areas of the CELDT in the first 3 years of enrollment in a TBE program; the students scored lower than their SEI peers in their oral proficiency. This may partly be due to the fact that in Kindergarten the students with lower English proficiency were placed into the TBE program, and students with higher English proficiency were placed in the SEI program. Interestingly, the gap between the SEI and TBE students' oral proficiency scores decreased over the first 3 years. In fact, in the last year, the TBE students scored higher than the SEI students in their oral proficiency. As for literacy scores, in grade 2, the SEI students outperformed the TBE students, but in grade 3, the TBE students had a higher average in their literacy scores than the SEI students, although it was not statistically significant for both oral and literacy proficiency.