In 1992, Middlebury College adopted a new residential system that divided all students into one of five Commons. This great change came after the abolition of fraternities had altered the social system on campus and the administration knew that a new system had to established. The five Commons are named after important College figures: President Jeremiah Atwater, President Ezra Brainerd, Dean Eleanor Ross, Professor Reginald Cook, and Dean Erica Wonnacott. The Commons provide social programming and a close-knit student government structure. The Commons residential system has evolved greatly since 1992 and currently the Commons system is based on the "4/2" model. The 4/2 model has students always remain part of the Commons they are assigned as freshmen, but only live in Commons-specific housing for the first two years. Junior and senior year housing is determined by a lottery system and not by commons affiliation.