Scholarship has shown that writing groups are important sites of authority negotiation for student writers, yet little empirical research has examined how groups negotiate authority through conversation or how these negotiations influence students' developing expertise. Drawing on observations and interviews of an undergraduate thesis and a graduate dissertation writing group, I use the concept of "presentification" to analyze conversational moments in which group members referenced advisors, "making present" advisor authority to influence group collaborations. Specifically, I analyze these moments to show how writing groups can serve as low-stakes communities in which students negotiate their emerging sense of authority. I found that whereas less experienced writers looked to advisors to solve writing problems and used advisor authority to stand in for disciplinary expertise, more experienced writers voiced advisor guidance to help pose writing problems and negotiate their own stance as disciplinary experts. This study thus theorizes one process through which student writers negotiate emerging authority across sites of literate practice and in collaboration with others who may not themselves be members of the same disciplinary community.