Traditionally, colleges assign roommates using a questionnaire that asks about various personal preferences, including neatness and messiness, musical preferences and study habits.
Are Guys Allowed In Girl Dorms? (FIND OUT!) - SavvyCollegeGirl
Off to College: How to Choose Your Freshman Dorm-and Roommate - Position U 4 College
What is 'Room Draw'? | Princeton University Admission