What Is a Prerequisite?

A prerequisite is a course, test score or other requirement that you must meet before you can enroll in a particular course. Prerequisites make sure students have the background knowledge needed to keep up. Calculus is a prerequisite for many engineering courses, and an introductory writing course may be a prerequisite for advanced composition.

How prerequisites work

Prerequisites are set by the department and listed in the course catalog. The registration system often checks them automatically and blocks enrollment if your record does not show the required course with a minimum grade, commonly a C or higher. Some prerequisites can be met with placement test scores, transfer credit, advanced placement or equivalent experience.

Prerequisites form chains. To take a final-year course, you might need a third-year course, which needs a second-year course, which needs an introductory one. That is why planning early matters, especially for majors with long sequences such as sciences, engineering and nursing.

Why they matter for planning

If you skip ahead without realizing a prerequisite is missing, you may be removed from the class or lose a term of progress. Courses that are offered only once a year can delay graduation if you miss the sequence. Check prerequisites when you plan each semester, and map them across your whole degree.

What to do if you lack one

Talk to the instructor or advisor. Explain how you have covered the material, for example through a previous course at another school, work experience or independent study. Many departments grant an override when there is good evidence. If not, a summer course or a placement exam may help.

Related terms

See corequisite, degree audit, elective and articulation agreement. A prerequisite is different from a general education requirement, which applies to your degree and not to one course.