An interdepartmental (ID) major consists of combining courses from two different academic departments into a single major. Generally, if the departments are in different academic divisions (e.g. humanities, social sciences, natural sciences), then the ID major requires eight courses in each department. If the departments are in the same division, then the ID major requires eight courses in one department and six in the other.
Specific ID major requirements vary depending on the departments chosen, so read the requirements for the specific departments you want to combine. Students with ID majors typically undertake a senior capstone research project that relates the two disciplines.