Given that arts integration and engaging in arts processes is a productive pathway to helping learners make deeper connections to content and making sense of their world, the work to be done is supporting a shift in teaching practices. This dissertation examines artist/teacher partnerships across periods of planning, teaching and reflection to show how the partners engage in distributed integration through various models of arts integration partnerships. This study aims to theorize the practice of being a teaching artist, bringing arts integration into the formal classroom, as a partner to a classroom teacher. I build on work in arts integration as well as our understanding of what a teaching artist is, and how they position their work in the classroom, including what it means for teachers and artists to work collaboratively. I do this using a conceptual framework to ground my analysis, based on distributed cognition theory and sociocultural learning theory. Specifically, this dissertation examines partnerships between three teaching artists and seven classroom teachers as they work together to integrate arts into STEM (science, technology, engineering and math) curriculum in elementary school classrooms through a STEAM residency program administered through a local youth arts organization. Through observations of planning meetings as well as in-class teaching time, I analyze the teaching artist/teacher co-teaching partnership, including how the two negotiate how arts should be integrated into the curriculum, how teachers support teaching artists during instructional time, and the impact this partnership has on both the artists' and teachers' professional development as educators. [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/en-US/products/dissertations/individuals.shtml.]