A 29th-round draft pick by the Boston Red Sox in 2000, Gabbard started the 2006 season with Boston's Double-A affiliate Portland and posted a 9-2 record with a 2.57 ERA in 13 starts. Promoted to Triple-A affiliate Pawtucket on June 23, he went 1-3 with a 4.97 ERA in five starts. He earned a promotion to the Boston Red Sox on July 21 to replace Tim Wakefield, who was on the disabled list. In his Major League debut on July 22, he allowed two earned runs in 5 2/3 innings to the Seattle Mariners and was charged with a loss. Gabbard's first major league win was on September 5 against the Chicago White Sox. Gabbard was solid, going 7 shutout innings, surrendering three hits and striking out six in a 1-0 Red Sox win.