2006 NCAA Division I Men's Basketball Tournament
The 2006 NCAA Division I Men's Basketball Tournament involved 65 teams playing in a single-elimination tournament to determine the national champion of men's NCAA Division I college basketball as a culmination of the 2005–06 basketball season. It began on March 14, 2006, and concluded on April 3 at the RCA Dome in Indianapolis, Indiana.

None of the Tournament's top seeds advanced to the Final Four, the first time since 1980 that this occurred. For the second time in history, a team seeded 11th advanced to the Final Four as George Mason of the Colonial Athletic Association won the Washington, D.C. region. They were joined by Atlanta region winner LSU (who was the first team to advance to the Final Four as an 11-seed in 1986), Oakland region winner UCLA, who had not made the Final Four since they won the National Championship in 1995, and Minneapolis region winner Florida, who had not made the Final Four since their runner-up finish in 2000 also in Indianapolis.

Florida won its first-ever national basketball championship by defeating UCLA 73–57 in the final game. Florida's Joakim Noah was named the Most Outstanding Player of the NCAA Tournament.

George Mason's run was one of several upsets by lower-seeded teams in the tournament. For the second consecutive year, a No. 14 seed beat a No. 3 seed as Northwestern State defeated Iowa. No. 13 seed Bradley also defeated No. 4 seed Kansas and advanced to the Sweet Sixteen by defeating No. 5-seeded Pittsburgh in the Second Round. Two No. 12 seeds won as well, as Montana and Texas A&M both won their respective First Round matchups. For the second straight year, Milwaukee won as a double-digit seed, this time as the No. 11-seeded Panthers defeated Oklahoma in the first round.

Tournament procedure and locations

A total of 65 teams were selected to participate in the tournament. Of that total, 31 of the teams earned automatic bids by winning their conference tournaments. Penn earned an automatic bid by winning the regular-season title of the Ivy League, which did not conduct a conference tournament. The remaining 34 teams were granted "at-large" bids, which are extended by the NCAA Selection Committee.

The initial game on March 14 officially named the Opening Round game, but popularly called the "play-in game", had Monmouth, winner of the Northeast Conference Tournament, facing Hampton, who won the Mid-Eastern Athletic Conference Tournament, for a chance to play top seed Villanova in the First Round of the Tournament. Monmouth defeated Hampton, 71–49, to advance to play Villanova.

All teams were seeded from 1 to 16 within their regions. The Selection Committee seeded the entire field from 1 to 65. In a practice used since 2004, the ranking of the four top seeds against each other would determine the pairings in the Final Four. The top overall seed would be seeded to play the fourth overall seed in the national semifinals, should both teams advance that far. In 2006, these rankings were as follows: No. 1 Duke, No. 2 Connecticut, No. 3 Villanova, and No. 4 Memphis.

The first and second-round games were played at the following sites:
March 16/18:
Cox Arena, San Diego, California (Host: San Diego State University)
Greensboro Coliseum, Greensboro, North Carolina (Host: Atlantic Coast Conference)
Jacksonville Veterans Memorial Arena, Jacksonville, Florida (Host: Jacksonville University)
Jon M. Huntsman Center, Salt Lake City, Utah (Host: University of Utah)
March 17/19:
American Airlines Center, Dallas, Texas (Host: Big 12 Conference)
The Palace of Auburn Hills, Auburn Hills, Michigan (Host: Oakland University)
University of Dayton Arena, Dayton, Ohio (Host: University of Dayton)
Wachovia Center, Philadelphia, Pennsylvania (Host: Atlantic 10 Conference)

The four regionals were officially named after the four host cities, a practice which also began in 2004. However, in 2007, the NCAA returned to naming regionals by their geographic location. The 2006 regionals were: 
March 23/25:
Atlanta Regional, Georgia Dome, Atlanta, Georgia (Host: Georgia Institute of Technology)
Oakland Regional, Oakland Arena, Oakland, California (Host: University of San Francisco)
March 24/26:
Minneapolis Regional, Hubert H. Humphrey Metrodome, Minneapolis, Minnesota (Host: University of Minnesota)
Washington, D.C. Regional, Verizon Center, Washington, D.C. (Host: Georgetown University)

Each regional winner advanced to the Final Four, held on April 1 and 3 at the RCA Dome in Indianapolis, hosted by Butler University and the Horizon League. This was the fourth and final time the RCA Dome would host the Final Four before moving to Lucas Oil Stadium. For the first time, the tournament came to Jacksonville, Florida, playing games at the Jacksonville Veterans Memorial Arena. This marked the sixth city and fifth metropolitan area in the state of Florida to host games. The 2006 tournament also marked the final tournament games held at the Huntsman Center and Oakland (now Oracle) Arena. Tournament games have moved to downtown Salt Lake City and the Vivint Smart Home Arena since, to take advantage of more amenities there as opposed to the campus of the University of Utah. As for Oakland, there are currently no games scheduled in the near future, with 2022 scheduled to host games at the new Chase Center in downtown San Francisco. As the Golden State Warriors will also be moving to the Chase Center once it opens, it is unclear what will happen to the Oracle Arena once their primary tenant moves out.

Qualifying teams

*Opening Round participants

Bids by conference

Bracket
(*) – Number of asterisks denotes number of overtimes.

Opening Round game – Dayton, Ohio
Winner advances to Minneapolis Regional vs. No. 1 Villanova.

Atlanta Regional

Oakland Regional

Minneapolis Regional

Washington, D.C. Regional

Final Four – Indianapolis, Indiana

Record by conference

*Monmouth University won the Opening Round game.

The America East, Atlantic Sun, Big South, Big West, Ivy, MAAC, MAC, MEAC, Ohio Valley, SoCon, SWAC, Mid-Continent, and Sun Belt conferences all went 0–1.

The columns R32, S16, E8, F4, and CG respectively stand for the Round of 32, Sweet Sixteen, Elite Eight, Final Four, and Championship Game.

Announcers
Jim Nantz and Billy Packer – First & Second Round at Philadelphia, Pennsylvania; Minneapolis Regional at the Hubert H. Humphrey Metrodome; Final Four at Indianapolis, Indiana
Dick Enberg and Jay Bilas – First & Second Round at San Diego, California; Atlanta Regional at the Georgia Dome
Verne Lundquist and Bill Raftery – First & Second Round at Auburn Hills, Michigan; Washington, D.C. Regional at the Verizon Center
Gus Johnson and Len Elmore – First & Second Round at Dayton, Ohio; Oakland Regional at the Oakland Arena
Kevin Harlan and Dan Bonner – First & Second Round at Greensboro, North Carolina
Ian Eagle and Jim Spanarkel – First & Second Round at Salt Lake City, Utah
Craig Bolerjack and Bob Wenzel – First & Second Round at Dallas, Texas
Tim Brando, Stephen Bardo, and Mike Gminski – First & Second Round at Jacksonville, Florida

Greg Gumbel once again served as the studio host, joined by analysts Clark Kellogg and Seth Davis.