Preservice teachers must have opportunities in their university teaching programs to apply theories of second language learning. Courses in second language acquisition and English as a second language methodology are essential to prepare mainstream teachers for teaching culturally and linguistically diverse learners. Additionally, creating a connection between coursework and field experiences is fundamental for preservice teachers to practice specialized teaching strategies. The specific problem of interest in this qualitative study was the alignment of second language acquisition knowledge to elementary preservice teachers' practices. Employing a qualitative comparative case study, the researcher's purpose was to explore elementary preservice teachers' perceptions of their knowledge in second language acquisition and its connection to their instructional practices with English language learners. The researcher addressed preservice teachers' perceptions of how they apply theories of second language learning within one university teaching program in the Southeastern United States. Data collection included emailing pre-course and post-course questionnaire survey links to eligible elementary education students. Using a cross-case analysis, the researcher compared similarities and differences in preservice teachers' responses. During the analysis, data was coded, and patterns and themes were identified. The results revealed most preservice teachers had very little or no experience working with English learners. However, the preservice teachers, who were currently or previously enrolled in additional ESL courses, found their current and past courses to be mostly effective in preparing them to help English learners. Furthermore, the participants who were enrolled only in elementary education courses, listed several principal instructional strategies as beneficial in helping English learners. Nevertheless, the results of these preservice teachers' perceptions regarding their ESL knowledge and skills demonstrated the participants believed they were missing the background needed to effectively teach English learners. Based on this study's results, three recommendations were given: requiring specific ESL coursework; including meaningful ESL teaching activities; and offering both early and latter field experiences with English learners. Further research could include studies that increase the number of university teaching programs and preservice teachers participating in the U.S. Additionally, individual interviews and focus groups could be conducted with both preservice teachers and education faculty. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]