Not all students with disabilities receive special education accommodations in science class. Without special education support, students with disabilities are unable to comprehend and apply science concepts. Implementing a co-teaching model could be a remedy for this lack of supports. Framed by constructivist theory, this study sought to determine if there was a difference in science assessment scores between students in a co-taught science class and those in a regular education science class. Following a pretest-posttest control group design, this study examined the relation between two teaching models and achievement in science. Using a convenience sample of 84 students drawn from a population of 144 fourth grade special education students in a public school district located in the Southeastern United States, analysis of variance was used to compare the mean growth of the two groups. The data revealed no statistically significant difference in mean gain scores between the two groups. Additional studies using a larger sample and longer trial are needed. Implications for social change include understanding instructional strategies that allow educators to differentiate for diverse learners in mainstreamed classrooms as well as removing barriers for underrepresented groups, thereby allowing equal access to science related professions. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]