This paper examines the literacy results of English language learners (ELLs) in two California schools following either the 50/50 or the 90/10 dual language (DL) program model. The purpose of this paper is to provide a literature review of dual language programs with an analysis of two schools’ websites and literacy assessment data in order to determine the effectiveness of each program model in establishing strong foundational literacy skills and fostering the prolonged academic success of ELLs. California provides various options for the bilingual education of its increasing immigrant population. Under the umbrella of bilingual education, dual language programs aim to provide students with instruction in two languages which will allow them to become fully bilingual and develop biliteracy skills. The intended purpose of biliteracy is for students to demonstrate reading and writing proficiency in both instructional languages. Although California implements a variety of dual language program models, this paper provides an overview and comparison of the 50/50 and 90/10 models as they are implemented in two California schools with similar demographics. This paper provides an analysis of the English Language Arts/literacy results of ELLs under both program models as depicted on the California Assessment of Student Performance and Progress to determine which model is most effective in its literacy instruction of language minority students. The findings indicate that ELLs demonstrate higher levels of literacy proficiency under the 90/10 program model. These findings have implications for native language proficiency and the preservation of the mother tongue.