Class you want not listed? Take it independently!
You can register for practically any Cornell class listed in Courses of Study if you can find a professor willing to supervise the coursework through independent study. (This may be an actual independent study class or it may be any other course that a faculty member is willing to offer on a tutorial basis.)
Once you have identified a professor willing to supervise your study, please follow the registration steps outlined on the Independent study enrollment page. This must be done at least two weeks prior to beginning the independent study class.
In addition, a group of students (at least five) wishing to enroll in a specific class not scheduled for the summer may write and sign a letter or e-mail and send it to the School of Continuing Education and Summer Sessions registrar (B20 Day Hall Ithaca, NY 14853-2801, or email@example.com) requesting that the class be added to the roster. The Summer Session will then try to arrange for that course to be offered.