This dissertation focused on comparing the academic achievement and language proficiency in both English and Spanish of students at risk for language and learning difficulties, with bilingual typically developing students in two bilingual educational contexts: English as a Second Language program and Spanish two-way immersion program. Data was gathered and analyzed using a quantitative research method. This research design used several types of data collection procedures to measure academic achievement and language proficiency: standardized reading and mathematics assessment, English proficiency test, and Spanish proficiency test. Results were analyzed using descriptive statistics. This research shall serve as one more piece of the puzzle that delineates what the best practice is with regards to the education of culturally and linguistically diverse students. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]