This qualitative study focuses on critical incidents identified by three U.S. PhD students as they reflected on the process of writing qualifying examinations. This study is couched in sociocultural conceptions of literacy, which view the qualifying exam as a social practice. Extending previous research of doctoral student writing and utilising a form of critical incident analysis, we found that navigating (1) the writing process, (2) claims to authority, and (3) relationships with mediational agents were important factors in participants' successful academic writing and advanced disciplinary belonging. Practical implications suggested by this study include exploring the genres that lead to and support qualifying exams, providing conversational workshops with doctoral students and faculty about the academic writing process, and explicitly supporting students' identity development through the writing process. This project also supports the value of critical incident analysis as a tool for studying conceptual transformations in academic writers as they transition from doctoral students to candidates to professionals in higher education.