This study explored the perceptions of general and special education teachers. The theoretical framework set the foundation for the literature review and provided insight to the proposed conceptual model called, The Trifecta. This non-experimental, quantitative, descriptive study used an online survey to learn to what extent elementary co-teachers in the Mid-Hudson Valley region of New York State receive professional development, their perception of administrative support, and their ability to apply co-teacher competencies and behaviors in the classroom. Descriptive statistics were used to analyze data. Results revealed minimal to no preparation amongst both special and general education teachers for co-teaching. Respondents reported administrative support of common planning time, but a lack of support for ongoing professional development, unclear role definitions, and unclear expectations for the co-teaching environment. Respondents indicated a need for professional development before and during co-teaching. Two identified barriers to success were a lack of parity in the classroom and misunderstanding of the effective use of co-teaching models. Respondents identified "One-Teach" and "One-Support" as common types of co-teaching, which historically has been identified as the least impactful approach. The results of this study indicate a need for; college coursework related to co-teaching. a continuous improvement model to support co-teaching practices, and a vision for a culture of inclusivity. This research deepens society's understanding of what it means to co-teach, meet all students' needs, see disability as diversity, and avoid assumptions about what is considered "normal." School divisions can create a supportive student learning environment by improving co-teachers' instructional practice. [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.]