This qualitative action research study examined teachers' perceptions about co-teaching and its effectiveness as an instructional model for students with disabilities. One-on-one interviews were conducted with eight elementary and secondary teachers from a medium sized school district located in Southwest Ohio that has a students' with disabilities population exceeding 24%. Four of the participants were regular education teachers and four were special education teachers assigned to elementary and secondary grades who are currently implementing co-teaching in their classrooms. Analysis of the data revealed that participants overwhelmingly perceive co-teaching to be an effective instructional model. Participants identified higher student achievement, academic growth, greater student understanding, higher test scores, and better differentiated instruction as benefits of co-teaching. Four themes emerged based on data analysis: team teaching is the most effective co-teaching strategy, co-teaching increases academic achievement, lack of planning time is a concern, and relationships are important in a co-teaching classroom. [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.]