2005 NCAA Division I-A football rankings

Three human polls and one formulaic ranking make up the 2005 NCAA Division I-A football rankings, in addition to various publications' preseason polls. Unlike most sports, college football's governing body, the National Collegiate Athletic Association (NCAA), does not bestow a National Championship title for Division I-A football. That title is bestowed by different polling agencies. There are several polls that currently exist. The main weekly polls are the AP Poll and Coaches' Poll. About halfway through the season, two additional polls are released; the Bowl Championship Series (BCS) Rankings and the Harris Interactive Poll.

During the 2005 season, 34 different teams appeared in the rankings by the major polls, but two teams, USC and Texas, held the top two spots throughout the course of the season.

BCS rankings
The BCS rankings are a based on a formula composed of the Coaches' Poll, the Harris Interactive Poll and six computer rankings. These rankings are usually released around the seventh week of the season. It is the results of this poll that decide which teams play in which bowl games as well as which two teams will play in the BCS National Championship Game. The BCS Rankings are generated by taking the points received in each poll individually, and dividing by the total points that a single team could earn if they were ranked #1 by every member. For example, the maximum total points in the Coaches' Poll is 1550, and if a team earns 1387 points, their score in the BCS for the Coaches' Poll would be .895. The BCS Rankings then does the same for the Harris Interactive Poll. Next, the highest and lowest rankings of the 6 computer rankings are dropped, the remaining 4 combined with the points (again awarded by position) and divided by 100. The three percentages are then averaged, and the highest average is then awarded 1st place in the BCS Rankings.

AP Poll
The AP Poll is the oldest poll still in use. This poll is compiled by sportswriters across the nation. This season was the first season since the inception of the BCS that the AP Poll was not included in the BCS formula. The AP ordered a cease and desist to stop the BCS from using their poll and the BCS complied and created the Harris Interactive Poll in response. The poll operates identically to the Coaches' and Harris Polls, except there is no inclusion into the BCS.

Coaches' Poll
The Coaches' Poll is the 2nd oldest poll still in use after the AP Poll. It is compiled by a rotating group of 62 college football Division I head coaches. Each voting member ranks teams from 1 to 25. Each team then receives points for their ranking in reverse order: Number 1 earns 25 points, number 2 earns 24 points, and so forth. The points are then combined and the team with the highest points is then ranked #1; second highest is ranked #2 and so forth. Only the top 25 teams with points are ranked, with teams receiving first place votes noted the quantity next to their name. Any team receiving votes after the top 25 are listed after the top 25 by their point totals. However, these are not real rankings: They are not considered #26, #27, etc. The maximum points a single team can earn is 1550.

Harris Interactive Poll
The Harris Poll is the newest poll as it was created in 2005 to replace the AP Poll in the BCS formula. It consists of former players, coaches, administrators, and current and former media who submit votes for the top 25 teams each week. The panel has been designed to be a statistically valid representation of all 11 Division I-A Conferences and independent institutions. The poll operates identically to the Coaches' Poll, except with 114 members, the point values of the highest ranked teams are higher than the Coaches' Poll. The maximum points a single team can earn is 2850 points. The poll ends at the conclusion of the regular season, and does not produce another poll after the bowl games.

Preseason polls
Various publications release their preseason top 25 months before the season commences. Each poll uses different methodologies. For instance, some rank the teams based on their perception of the team's strength going into the season and some rank them based on their perception of the team's possible record at the end of the season. These are different because one team may be stronger but have a tougher schedule and another team may be weaker but have a weaker schedule and both teams may end the season with the same record. The 2005–06 BCS champions Texas Longhorns are highlighted in gold.