Most undergraduate courses at St. Thomas are 4-credit courses, although some departments also offer 0-credit or 2-credit courses. Each course is assigned a subject-area code consisting of four letters, which designates the department or discipline, followed by a three-digit number. For example, ENGL 121 is the English course numbered 121.

Courses offered through the Dougherty Family College have numbers that begin with either 1 or 2, which indicates they are lower-division courses.

The number of class meetings for a course varies with the nature of the course. Class Finder indicates the days and times each class meets.