The four, who recently won Gold Gloves, on Thursday also earned the Silver Slugger in voting by managers and coaches. The honor is given to the top offensive performers at their respective positions.
Mauer, the Twins catcher, won the award for the second time. He won his second batting title, hitting .328, with nine home runs and 85 RBIs last season.
Pedroia becomes the first Red Sox second baseman to receive the honor after batting .326 with 17 home runs and 83 RBIs. The 25-year-old led the majors with 54 doubles, tied Ichiro Suzuki for first with 213 hits, and ranked second with 118 runs and 61 multi-hit games, both AL highs.
At 26, Sizemore is the youngest Cleveland player to win since Jim Thome in 1996. Sizemore hit a career-high 33 homers and had 38 steals this
Wright won his second consecutive award and is the first Mets player to accumulate four seasons with 100 or more RBI.
"It's a very prestigious award and I am proud to win it, considering the people who vote for the award," Wright said in a statement. "This honor will help motivate me to an even better season in 2009."
Selections for the Louisville Silver Slugger Award were based on a combination of offensive statistics including batting average, on-base percentage and slugging percentage, as well as the coaches' and managers' general impressions of a player's overall offensive value.