Online courses are often criticized for having lower retention rates than traditional courses, especially introductory courses. This study aimed to determine whether there was a relationship between online and traditional instructor personality traits and course completion rate for introductory course instructors at a higher education institution in the Western United States. Instructor personality traits, as measured by the NEO Five-Factor Inventory-3 (NEO-FFI-3), were correlated with student course completion rate. Independent t tests were used to determine whether the relationship differed as a function of modality. There were no statistically significant relationships found between online and traditional instructor personality traits and course completion rate, but there were statistically significant differences between modalities for extroversion, agreeableness, and course completion rate. The results imply the traditional modality better supports individuals with these traits and allows for greater expression of the traits. The findings provide a greater understanding of the diversity among teachers in different modalities.