This mixed-methods study investigated the perceptions of elementary teachers in their co-teaching relationships and the impact those relationships had on instruction. The study was based on teacher and principal questionnaire surveys and semi-structured teacher interviews. The study investigated co-teaching that took place during the 2019-2020 school year to gain a full understanding of the co-teaching relationship. It was anticipated that the knowledge gained from this study would offer insight into the impact of integrated, co-taught environments for school administrators, co-teachers, and preservice teachers. [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.]