From the New Student FAQ (
http://apps.carleton.edu/student/new/faq/):
"Residential Life staff complete housing assignments for new students in late July. As soon as all new students are housed, we send a packet of information which includes your room assignment and the name, address, phone number and e-mail address of your roommate(s). We hope that when you receive your assignment, you will contact your roommate(s) to become acquainted."