The study addressed the gap in fifth-grade science proficiency between English language learners (ELLs) enrolled in two different science programs in a large school district in the Southeast United States. The Inspire program was implemented in 125 schools, while a combination of Inspire and Promoting Science among English Language Learners (PSELL) developed to facilitate science learning for non-English learners, was implemented in 25 schools. A concurrent mixed-methods case study design was used to examine how instructional practices of each program were (1) aligned with the instructional framework of the Sheltered Instructional Observation Protocol (SIOP), (2) how the two programs supported the acquisition of content-specific learning for fifth-grade ELL students (qualitative), and (3) whether there was a difference in science proficiency between ELLs who participated in one program or the other program. Thematic analysis based on SIOP was used to analyze the qualitative data from the six teacher interviews, three teachers from each science program. Data from the Florida Comprehensive Assessment Test were used to compare the proficiency levels of the 96 fifth-grade ELLs in the two schools. Teaching practices in the combined Inspire + PSELL program were more closely aligned with the SIOP framework. A Mann-Whitney U test revealed a significant difference in achievement between students taught with Inspire (Md = 39.93, n = 28) and those taught with Inspire + PSELL (Md + 52.03), U = 712, z = -2.579, p = 0.010, r = 0.30) in favor of Inspire + PSELL. The finding was consistent with the qualitative study. The study may bring positive social change in district policy for fifth-grade science by expansion of the more effective science program or through staff development of the teaching strategies aligned with PSELL and SIOP. [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.]