Composition courses have a contentious relationship with textbooks. On one hand, textbooks grant legitimacy to a eld that historically struggled with its image of being in service to other elds. On the other hand, in a course designed to teach students authorial agency, discursive sensitivity, audience awareness, and the dialogic nature of writing, textbooks' typical monolithic anonymity and ethos of sacred infallibility puts them at odds with the content they contain. Further, because textbooks are often written by prominent, established scholars long separated from the undergraduate experience, theoretically sound and widely accessible textbooks can be hard to find. To address these issues, this article proposes context-specific, student-generated textbooks as a way to achieve three goals: First, to challenge the traditional understanding of expertise by emphasizing constructed knowledge. Second, to leverage student positionality, allowing students to write as authorities while learning the discipline. And third, to become a platform for discourse within an institution's composition program. Overall, this article argues that creating textbooks gives students practical experience with meaningful writing situations and genuine, familiar audiences. By creating course materials, students learn to assert authorial expertise, build audience-aware writing strategies, and enact iterative revision practices.