This qualitative exploratory single case research study used observations, semi-structured interviews, and document analysis to explore co-teachers' perceptions of the implementation of a co-teaching instructional model in elementary school general education classrooms with clusters of English learners (EL) in attendance. A total of four co-teaching teams participated in this study; each team included one EL specialist and one general education teacher, for a total of eight participants. The main research question was, "What perceptions do 1st through 6th grade English learner specialists and general education teachers have of the implementation of an English learner co-teaching environment in Gates School District?" The researcher analyzed the data collected from interviews, observation, and lesson plan analysis using the MAXQDA software, from which four themes emerged regarding the successful implementation of co-teaching strategies: finding clarity in the roles and responsibilities of co-teachers within their teams; effective time management of the co-planning period; desire for professional development opportunities; and an understanding of collective efficacy by learning from each other. Based on the specific findings of this study, implications for practice include support in determining each team member's role, a district-implemented co-planning master schedule, professional development, and lesson planning templates for the co-teachers to use and review. [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.]