Adding a Course
The drop/add period closes at the end of the second week of classes each semester. During the first week of class, you can use ACES Web to add a course if there are seats available. Check the course listings with the Registrar's Schedule Search page (select the "Return only classes with space available" check box). Be sure that you check for prerequisites that might be required for the course. No permission number is necessary during the first week, except for courses that always require consent of the instructor.
During the second week of classes you can still add a course if you obtain a permission number from the instructor. You'll use the permission number when you add the course through ACES.
After the drop/add period closes, you can no longer add a new course. However, during the week immediately following drop/add (the Schedule Correction Period) you are able to add a course that you have been attending since before the end of the drop/add period. You should always review your schedule as soon as the drop/add period is over every semester to be sure you're enrolled in the correct courses.