There was considerable variation among postsecondary instructional faculty and staff regarding the extent to which they taught undergraduates. For example, among both part- and full-time instructional faculty and staff who taught classes at 4-year doctoral institutions, instructors/lecturers were more likely than assistant, associate, or full professors to teach undergraduate classes, and to teach such classes exclusively. Faculty with a lower degree (e.g., a bachelor's or lower degree) were generally more likely than those with a doctoral or first-professional degree to teach undergraduate classes and to teach them exclusively.

At 4-year doctoral institutions, part-time faculty were more likely than full-time faculty to indicate that all of their classes were at the undergraduate level, although no difference was found between the two groups regarding teaching at least one undergraduate class. In addition, at 4-year doctoral institutions, nontenure-track faculty were more likely than tenured faculty to report teaching undergraduate classes exclusively. There was also variation across teaching fields. At 4-year doctoral institutions, both full- and part-time faculty in the humanities were more likely than average to report teaching undergraduate classes and teaching such classes exclusively, whereas those in the health sciences were less likely to do so.