Relationships with teachers are a central component of a student's school environment, and have been shown to be related to school engagement and persistence in secondary school. Working alliance is a conceptualization of professional relationships that emphasizes not only the emotional bond between a professional and their client, but also their collaboration on the goals and tasks of their work together. While this theory has garnered considerable support in the fields of counseling and healthcare, working alliance has only recently begun to be investigated in an education setting. The present study sought to investigate working alliance between students and teachers as a broader framework for relationships in a high school setting. Specifically, the primary objective was to examine the use of the working alliance framework in teacher-student relationships to predict risk of high school student drop-out. A series of multiple regressions was used to test this objective. Results demonstrated that student-rated school working alliance predicted risk of drop-out, and that the relationship was partially mediated by student engagement. These results provide evidence for the validity of the construct of working alliance as a useful conceptualization for teacher-student relationships, and enhance our understanding of working alliance in a secondary school setting. Implications for educators and practitioners are discussed.