Mathematics teacher educators enact inquiry-based preparatory courses with the underlying expectation that their students (prospective teachers) will take ownership (authority) of their mathematical learning through sharing their ideas and collaboratively discussing the reasonableness of their shared ideas. Yet, prospective teachers' expectations are often not yet in alignment with those of mathematics teacher educators, instead they enter these courses expecting their instructors to provide clear examples and directions for how to solve mathematics problems. This project investigates this dynamic through an authority lens, seeking to understand and characterize different views of authority prospective teachers hold and the impact these views have on their learning experiences and on their development of an internal source of authority. Understanding this dynamic is crucial in courses designed to prepare prospective teachers to teach mathematics, as their experiences in preparatory mathematics content courses have the potential to shape their future practice. Through an analysis of survey responses and interview transcripts I synthesized how participants, in their own words, described their understanding of authority in mathematics classrooms, how their descriptions of their experiences in learning to justify indicated a range of views of authority, and how a course design utilizing shared interactive slides facilitated prospective teachers' understanding of their authority to reason about mathematics. These syntheses inform mathematics teacher educators' practice as they, together with their students (prospective teachers), interrogate norms of how authority operates in mathematics education. [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.]