The residential college system is the focus of the undergraduate experience at Rice University. This takes the place of the typical American university on-campus housing organization of dorms and fraternity/sororities. When a student becomes an undergraduate they are assigned to a residential college randomly (often simply referred to as 'college'), although "legacy" exceptions are made to assign students to colleges of which their siblings or relatives have been members.

Each college enjoys the same diversity of the greater university with regard to majors, ethnicity, personality, athletes, etc. Students remain a member of the college that they are assigned to for the duration of their undergraduate career. The majority of students prefer to live on campus for all four years, but shortage of spaces results in some students being "jacked" off campus each year. Students are guaranteed on campus housing for freshman year, and each college has its own system for determining how to allocate the remaining spaces (which are generally sufficient to accommodate all but one year of students). For example, colleges "kick off" a portion of either the sophomore or junior classes, who move off-campus at the end of the previous year and return to campus the next year if they so choose. Each college has its own set of buildings and commons or dining hall (or shares a "servery" with other colleges).

Students tend to develop extreme loyalty to their college and maintain friendly rivalry with other colleges, especially during events such as Beer Bike and O-week. As a result of this organization the colleges are the central social structure of the undergraduate population at Rice. When asked where they are from, students often reply with their college rather than their hometown. Students social groups tend to, but not always, revolve around their college. This has been the most significant criticism of the college system: that it tends to create groups of friends within a college to the exclusion of people in the other colleges. Another perennial issue is that some colleges are old, decrepit, or just plain ugly, while others are new, have larger rooms, or superior facilities, despite all students paying the same tuition and fees.

There are currently 9 residential colleges, including six colleges on the south side of campus and three on the north. Although each college is composed of a full cross-section of students at Rice, each college over time has developed its own personality and traditions to varying degrees. All colleges except Sid Richardson College ("Sid Rich") are organized around their own small quadrangle.

Baker College, slightly smaller than the other eight colleges, is officially the oldest and includes the original wood-panelled library and dining facility of the campus. It is named after Capt. James A. Baker, William Marsh Rice's lawyer who uncovered the plot by William Rice's butler. Baker was also the grandfather of James Baker III, Secretary of State to President George H.W. Bush and is the namesake of the Baker Institute for Public Policy. Traditions at Baker include freshman camping and a Christmas Tree hunt.

William Marsh Rice Jr. College ("Will Rice College") was the second college created, though its original dormitory building, originally called South Hall, is the oldest residential building on campus. Will Rice prides itself on its individualism and tends to focus on its extensive winning history in the annual Beer Bike competition. Will Rice was named after the nephew of William Marsh Rice, himself a contributor to the university.

Hanszen College, known for being mysteriously protective of a knight sculpture near their house, was the third college formed. It was soon followed by Wiess College. Wiess is the southernmost college on campus, and has a reputation for being somewhat insular, with a more distinct or visible set of traditions than the other colleges. The residents here refer to their community as "Team Wiess". Wiess moved into a new building in 2002 as the previous facility, once intended as only temporary housing, was rapidly becoming uninhabitable. Some feel that the new Wiess house somewhat resembles a prison, with corrugated looking roofs, steel mesh railings, and narrow passages overlooked by balconies.

Lovett College was built in the 1970s after the Kent State riots with an eye towards being riot-proof. Lovett is sometimes referred to as "the toaster" after its rectangular facade and brutalist design. Sid Richardson College is the tallest building on campus and was built a few years after Lovett, making Sid and Lovett sister colleges and arch-rivals.

Jones College and Brown College are the two original north colleges. These were followed in 2002 by the third north college, Martel College. As a result of its recent formation, Martel has few traditions thus far and is generally lambasted by the other colleges, though most do admit that its facilities are excellent.

In the past, the south colleges were the mens' colleges, while the womens' colleges were the (at the time) two north colleges. The physical separation made it easier to maintain propriety since reaching the womens' colleges required a long walk down an well-illuminated path still known as "Virgin's Walk."

Graduate students are not affiliated with the College System; most of them live off campus in local apartments, though there does exist a university-owned and operated complex of Rice Graduate Apartments . The complex has all the aesthetic appeal of a Retirement Home, but is still an improvement over the old "Grad House" on S. Main, which was formerly a sleezy "hourly rate" motel that Rice bought out and converted to graduate housing probably out of embarassment at having such a sleezy establishment right off campus. Whereas the old Grad House never had 100% occupancy, the newer Rice Graduate Apartments quickly fill up each school year. The complex is located near the museum district, with convenient shuttle service to and from campus.

The old "Grad House" was demolished and is now a fenced-in grassy field across from St. Lukes Hospital on South Main. The future of this lot remains uncertain.