Adventure education organizations use co-instruction as the dominant mode of staffing programs, largely for issues related to risk mitigation. Although the American adventure education field has paired co-instructors to run multiday wilderness courses as the default arrangement almost since its inception, theory, research, and subsequent training have focused predominantly on individual-leader paradigms. Research into the phenomenon of co-instruction, and the voices of co-instructors themselves, has been largely absent in the adventure education literature. This phenomenological study investigated the experience of co-instructors through in-depth qualitative interviews, which were transcribed and inductively analyzed for emergent themes. Co-instructing, at its essence, emerged as a negotiated relationship between co-instructors that shaped their professional, social, and personal success while in the field. In this study, the author elaborates the central themes of the "negotiated relationship" and discusses the meaning of co-instruction in peoples' lives. (Contains 1 table.)