Least restrictive environment (LRE) is defined as teaching children with disabilities alongside non-disabled children; these children have not been identified as students with disabilities. An inclusion setting is the integration of students with disabilities in the general education setting to provide the least restrictive environment. Inclusion settings for students with disabilities have become the norm in K-12 public education across the nation. The purpose of this quantitative, quasi-experimental study is to investigate the effects of training elementary teachers in the district Collaborative Teaching training on ESE and the changes in attitudes toward inclusion settings in the elementary classroom. There were 32 teachers from the science, technology, engineering, arts, and math (STEAM) elementary magnet school in west central Florida who volunteered to participate in the pre and post Multidimensional Attitudes Towards Inclusive Education Scale (MATIES). Sixteen teachers voluntarily participated in the Collaborative Teaching training on ESE strategies and resources and a nine-week online learning module. Sixteen teachers did not receive the training. The results from the Mixed ANOVA testing, Mann Whitney U tests, and paired sample t-test concluded that no significant difference was found between the two groupings. Thus the study failed to reject the null hypothesis. Further recommendations for the study include training all school teachers in order to have a better support system and cohesive understanding of inclusion as well as focusing on the impact of the training on teachers attitudes. [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.]