Most undergraduates live on campus in one of MIT's 12 Institute houses or 39 MIT-affiliated fraternities, sororities, and living groups. All unmarried first-year students must live in one of the Institute's residence halls—except those who commute from home. Each dormitory has a live-in housemaster, who is usually a senior faculty member. Students may elect to remain on campus following their freshman year, or move to a fraternity, sorority, or independent living group. The current number of undergraduates living on campus is 3,381.
More than 1,900 single graduate students live in MIT's five campus houses—Ashdown House (NW35), Edgerton House (NW10), Sidney-Pacific (NW86), Tang Hall (W84), and the Warehouse (NW30). Two campus apartment complexes, Westgate (W85) and Eastgate (E55), accommodate over 400 graduate and undergraduate students with families. About 80 graduate students live in undergraduate dorms as graduate resident tutors.