Collaborative teaching may provide classroom support, professional development, and mentoring for teachers (Gallo-Fox & Scantlebury, 2016; Guise et al., 2017; Friend et al., 2015; Rytivaara et al., 2019). Recent scholarship in music education has indicated that collaborative teaching may also provide a more holistic approach to student teacher preparation (Kim, 2020; Palmer, 2018; Vanderwerff, 2019). Yet, research has shown that strong teacher-to-teacher relationships are essential for collaborative teaching to benefit teachers (Pratt, 2014; Guise et al., 2017), and that a purposeful study and enactment of care may aid in the development of these positive relationships (Rabin, 2020). Nevertheless, collaborative teaching in music education has generally focused on collaborative teaching in higher education, or as an exploratory, temporary practice (Bartleet & Hultgren, 2008; Clauhs & Newell, 2013; Freer & Barker, 2008), making it difficult to determine how teachers may develop and maintain strong, caring relationships that foster collaboration. The aim of this research was to examine long-term collaborative teaching to understand what attributes contribute to successful collaborative teaching partnerships among secondary instrumental music educators. In this ethnographic study, I examined the collaborative teaching experiences and social practices of four secondary instrumental music educators over an eight-month period through the lens of Noddings's (2005, 2012, 2013) educational care theory. I used multiple methods of data collection such as interviews, observations, surveys, and artifacts to understand the context, attitudes, and approach these teachers used in working together. I utilized Gee's (2014) approach to discourse analysis to deeply explore the data and understand care across teachers' relationships. Collaborative teaching provided these four secondary instrumental educators with consistent support and professional learning. The teachers' collaboration thrived as they developed strong, caring relationships. Despite heavy teaching burdens, teachers felt less overwhelmed and isolated than in their previous teaching positions. Instead, the teachers expressed a sense of belonging and fulfillment from working collaboratively. Teachers' attitudes rather than their skills, experience, or specialty played a primary role in the development of their caring teacher-to-teacher relationships. These teachers were committed to working together, to helping one another in the classroom, and to maintaining and developing caring relationships. [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.]