Despite potential applications to educational contexts, the working alliance concept has largely been confined to psychotherapy intervention research. Some have explored theoretically related concepts (e.g., immediacy, rapport), but no measure currently exists of the working alliance between a teacher and student within an academic course. The aim of this study was to develop such a measure. Results of exploratory and confirmatory factor analyses led to the creation of the Learning Alliance Inventory (LAI), which contained three factors (Collaborative Bond, Teacher Competency, and Student Investment). Reliability and validity analyses indicated that the LAI has temporal stability, distinguishes between instructors, and correlates with numerical course grades when controlling for GPA. As a result, the LAI provides a psychometrically sound instrument for measuring aspects of student-teacher interactions pertaining to their collaborative, purposive work. As such, the LAI may prove helpful in furthering our understanding of student learning and teaching effectiveness.