
Leinart redshirted his first year (2001) and saw no action. As a redshirt freshman the next year (2002), he was a backup to future Heisman Trophy winner and current Cincinnati Bengals quarterback Carson Palmer, who was in his senior season at USC (one which would conclude with Palmer's Heisman victory). While Leinart appeared in a few plays during his freshman year, he threw no passes.
In his sophomore season (2003), Leinart beat out Matt Cassel, a redshirt junior who backed Palmer in the 2002, and Purdue transfer Brandon Hance for the starting job at quarterback. Going into the 2003 season, Carroll and his coaching staff selected Leinart not because he had set himself significantly ahead of the pack in practice, but because they needed a starting quarterback. There was some thought in the press that Leinart would merely hold the starting position until highly-touted true freshman John David Booty, who had bypassed his senior year in high school to attend USC, could learn the offense.
His first career pass was a touchdown against Auburn. Leinart would win the first three games of his career before the then-No. 3 Trojans suffered a 34-31 triple-overtime defeat at California on September 27 that dropped the Trojans to No. 10.
Leinart and the Trojans bounced back the next week in one of Leinart's most famous college moments against Arizona State. Leinart injured his knee in the second quarter and was not expected to play again that day, but he returned to the game and finished 12-of-23 for 289 yards in a 37-17 victory.
Leinart and the Trojans won their final eight games and finished the regular season 11-1 and ranked #1 ranking in the AP and coaches' polls. However, USC was left out of the BCS championship game after finishing third in the BCS behind Oklahoma and LSU. The Trojans went to the Rose Bowl and played University of Michigan. Leinart was named the Rose Bowl MVP after he went 23-of-34 for 327 yards, throwing three touchdowns and catching a touchdown of his own. The Trojans claimed the AP national championship.
In 13 starts, Leinart was 255/402 for 3,556 yards and 38 TDs with 9 INTs. He finished sixth in the Heisman voting (Oklahoma quarterback Jason White won the Trophy that year).
The Trojans started Leinart's junior season (2004) with victories in their first three games. On September 25, the Trojans played Stanford University. After Stanford took a 28-17 halftime lead, Leinart sparked the offense with a 51-yard pass to Steve Smith and scored on a one-yard sneak to cut the Cardinal lead to four points. Leinart and the Trojans were able to take the lead on a LenDale White touchdown rush and hold on for the victory, 31-28. Leinart completed 24 of 30 passes.
Leinart and the Trojans completed a perfect regular season, finishing 12-0, during which Leinart threw for a career-high 400 yards against Notre Dame. After an incomplete pass and a sack led to a fourth-and-nine situation with ninety seconds left at the Trojans' own 26-yard line, Leinart called a gutsy audible fade route at the line and threw deep against the Irish's man-to-man coverage, where Dwayne Jarrett caught the ball and raced to the Irish' 13-yard line, a 61-yard gain. Leinart moved the ball to the goal line as time dwindled and scored on a controversial QB sneak that gave the Trojans a 34-31 lead with three seconds to go, giving the Trojans their 28th straight victory and one of the most memorable and dramatic finishes in the history of the USC-Notre Dame rivalry.
He finished on a weaker note in the final regular season game against UCLA, as he was held without a touchdown pass for the first time in 25 starts. Nonetheless, Leinart was invited to New York for the Heisman ceremony, along with teammate Reggie Bush, Oklahoma's freshman sensation Adrian Peterson, incumbent Jason White, and Utah's Alex Smith. In what many had considered one of the more competitive Heisman

races, Leinart became the sixth USC player to claim the Heisman trophy.
In 2005, USC went wire-to-wire at #1 in the polls and earned a bid to the BCS title game at the Orange Bowl against Oklahoma, which was also 12-0 and had been on USC's tail all season. A dream matchup on paper (including White vs. Leinart, which was to be the first time two Heisman winners would play against each other), the Orange Bowl was a thumping, as Leinart threw for five touchdown passes on 18-for-35 passing and 332 yards to lead the Trojans to a 55-19 victory. Leinart received Orange Bowl MVP honors and the Trojans claimed their first BCS national championship (2nd straight #1 finish in the AP), extending their winning streak to 22 games.
Aside from a home game against Fresno State, the Trojans remained relatively unchallenged for the rest of the season, running their record to another 12-0 regular season and 34 wins in a row. Leinart, who was having arguably a better season than in 2004, was again invited to New York for the Heisman ceremony along with teammate Reggie Bush and Texas quarterback Vince Young. As a former Heisman winner, Leinart cast his first-place vote for Bush and ended up third in the voting behind the winning Bush and runner-up Young.
The Trojans advanced to the Rose Bowl to face Vince Young and No. 2 Texas in the BCS title game. The title game was considered another "dream matchup". Leinart himself had a great game, going 29-of-40 for a touchdown and 365 yards, but was overshadowed by Young, who piled up 467 yards of total offense and rushed for three touchdowns, including a score with 19 seconds remaining and two-point conversion to put the Longhorns ahead, 41-38. The Trojans lost for the first time in 35 games, and Leinart lost for just the second time in his 39 career starts.
Leinart finished his college career 807/1245 (64.8%) for 10,693 yards and 99 touchdowns with just 23 interceptions. He is USC's all-time leader in career touchdown passes and completion percentage, and is second at USC behind Palmer in completions and yardage. He averaged nearly 8.6 yards per attempt, and averaged only one interception every 54 attempts. He was 37-2 as a starter.
Source: wikipedia.org