In response to school cultures increasingly defined by high stakes testing, many teachers turn to arts integration as a method for meeting multiple learning objectives, but are less than prepared to do so. The "Collaborative Residency" program offers teachers an intensive course of study through collaborative work with artists as they co-plan and co-teach arts integrated units together. This qualitative case study describes how and to what extent collaborating with a teaching artist influences classroom teachers' professional growth and change. Teachers gained self-efficacy manifest through experiencing the arts as a joyful endeavor. This had a reciprocal effect on their behavior as they applied arts strategies and implemented formative assessment practices. Teachers also experienced restrictions concerning time, space and organizational support.