In this qualitative ethnographic and autoethnographic study, I examined a co-teaching partnership between a general education teacher and special education teacher in an international school. The school inclusion policy, which resulted from a shift in student demographics by admission of students with significant learning needs, supported the ecologies of knowing to encourage intentional engagement of co-teachers. The study goal was to tell the story of two co-teachers' experiences as they worked collaboratively to overcome the general education/special education teacher dichotomy in their classroom and develop a robust co-teaching partnership. The overarching question that guided the study was: "How do a general education and a special education teacher develop a co-teaching partnership?" Using an ethnographic and autoethnographic research methodology, the study offered the opportunity to collect and analyse thick descriptions of participant experiences. I analyzed reflective memos, co-planning meeting notes, field notes, classroom observation reflections and other artifacts to determine emerging themes. After two phases of inquiry over 10 months, we uncovered key elements of success about our co-teaching learning process to co-develop an ecology of co-teaching that would promote student achievement and access. Two findings contribute to understanding the intricacies of co-teaching partnerships: (1) Catalytic moments in a co-teaching relationship can contribute to a shift in practice; and (2) "in situ" professional development is key to co-creating an effective ecology of co-teaching. The co-instructors identified and addressed obstacles to co-teaching when they capitalized on catalytic moments. Despite the absence of common planning time, each teacher brought knowledge, experience, and skill to the partnership and learned to use each other's skills and dispositions to be productive. Other schools that use or intend to use co-teaching as a service delivery model can better understand how the teachers' professional learning is a complex and multidimensional process that has far-reaching consequences for teacher relationships and classroom practice. When teachers share certain values and beliefs, they can garner sufficient support from each other to co-teach inclusive classrooms. [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.]