Mastery-based testing is an assessment scheme that encourages students to learn from their mistakes and develop an understanding of material before moving on. For an entry-level course with large enrollment like College Algebra, this could allow some students to move at an appropriate pace for themselves. This paper outlines the changes made to make College Algebra at the University of Florida an asynchronous mastery-based course for the 500+ students who take the course per year and concludes with a series of lessons learned from the endeavor.