Every student is required to be affiliated with a House; this affiliation is determined the first week of one's first year during an event called "Rotation". Every day during Rotation new students eat lunch and dinner in a different one of the seven Houses, so new and old students get a chance to meet each other. At the end of the week the new students pick four Houses they would like to be considered for and rank them, and each House sends representatives to the "GGFL" (Great Grand Frosh Lottery) where they pick which students will live in what House in a process not unlike a pro sports draft. As a result, each house has its own character which is maintained over the years (although there have been some drastic changes in the past).
Within the Houses the students have considerable freedom to govern their affairs. For example, room assignment is performed by the Houses themselves (usually by a seniority system - each House does things slightly differently).
The seven Houses are divided into two complexes. Blacker, Dabney, Fleming, and Ricketts are the "South Houses", and were built in the 1920's in a Spanish style. Lloyd, Page, and Ruddock are the "North Houses", built in the '50s in a modern "institutional" style. Inhabitants of the Houses are known, in order, as Moles, Darbs, Flems, Scurves, Lloydies, Pageboys, and Rudds.