Graduate students 

A graduate student who has received a grade of B- or above or a P in a course may not repeat the course on a credit basis unless the individual department has made other arrangements.  (e.g., to meet qualifying exam grade requirements).

Course Repeat Application Form for Graduate Students

Undergraduate students

If a student has received a passing grade in a course, he or she generally may not repeat the course for credit unless the course no longer applies to the major or minor requirements or is not recognized by the department.

Course Repeat Application Form for Undergraduate Students