Turner began his career at Maryland as a redshirt in 2005 and then served as a reserve quarterback before he earned the starting position.

'"[3] At Chaminade, he led a pass-oriented offense and, during his senior year, accumulated 139 completions on 265 attempts, 2,047 yards, 16 touchdowns, and 11 interceptions.

In 2006, he served as the third-team quarterback behind starter Sam Hollenbach and reserve Jordan Steffy, but Turner saw no playing time during that season.

[8] In the game, he threw a 78-yard touchdown pass, which was caught by tight end Jason Goode rather than his intended receiver, Darrius Heyward-Bey.

[9][10] After a three-game losing streak, Turner led another upset win over a top-ten team, this time against eighth-ranked Boston College, 42–35.

[13] The following week Maryland played their regular season finale against NC State and both teams needed an additional win to attain bowl eligibility.

[20][21] After Maryland defeated 21st-ranked Wake Forest, 26–0, Turner was voted the ACC Player of the Week and ESPN named him an "On the Mark" quarterback.

[22][23] Against 16th-ranked North Carolina, Turner's split-second decision to hold onto the ball for a nine-yard run on fourth down and five put the team within range for the game-winning field goal, 17–15.

[24] The win improved Maryland's record to 7–3 and reasserted control over their ACC championship destiny, although they lost the next game against Florida State, 37–3, which ended the Terrapins' title hopes.

The following week against Boston College, Turner set career highs with 33 completions, 57 attempts, and 360 passing yards, but the effort fell short and Maryland lost, 28–21.

[25] In the postseason, the Terrapins played Nevada in the Humanitarian Bowl where Turner threw for 198 yards, one interception, two touchdowns including a 59-yard long, and a two-point conversion.

[26] At the end of the season, Maryland had beaten four out of their five Top 25-ranked opponents, a feat that was surpassed only by the teams in the BCS Championship Game: Florida and Oklahoma.

"[28] Before the season, Turner was added to the watch list for the Johnny Unitas Golden Arm Award, an annual honor bestowed upon the nation's top senior quarterback.

The most noteworthy of these were the momentum-changing 41-yard option run against NC State in 2007,[14] and the fourth-down nine-yard scramble into field goal range against North Carolina in 2008.

"[3] Regarding the 2008 summer practices, offensive coordinator James Franklin said Turner ranked in the middle compared with Jordan Steffy and Josh Portis in terms of completion percentage, fewest interceptions, and "explosive" plays that gained 16 yards or more.

[19] Head coach Ralph Friedgen who had offered critical or subdued assessments of Turners' practice, said his intensity grew after losing the starting position to Steffy prior to the 2008 season.

"[19] Among his Maryland teammates and coaches, Turner earned a reputation as an archetypal "laid-back" Californian and for remaining calm under pressure.

After the 2007 win over Rutgers, offensive tackle Scott Burley described his roommate Turner as "real calm [in the huddle] . . .

[3] He chose the University of Maryland partly based on its close proximity to Washington, D.C.[3] Turner's political views are liberal;[3] he is registered as a Democrat,[42] and has described himself as an idealist.

Turner and fellow quarterback Jordan Steffy, a conservative and supporter of presidential candidate Senator John McCain, were the most frequent debaters, while defensive tackle Dean Muhtadi was described as the primary instigator.

[42] During the summer of 2009, Turner held an internship on Capitol Hill working for Democratic Representative Steny Hoyer, the House Majority Leader and Maryland's fifth district congressman.

He is also interested in foreign cultures and expressed regret at being unable to spend a semester abroad because of college football.