Trigger groups for semi-automatic firearms have a frame, a hammer connected to the frame and movable between a cocked position and a striking position, the hammer being biased toward the striking position, a trigger element connected to the frame and movable by a user between a forward position and a rearward position, a selector connected to the frame and movable between at least a first position and a second position, a disconnector having a hammer engagement facility adapted to selectably engage the hammer, a disconnector control element movable between a first control position and a second control position, the disconnector being operably engaged to the disconnector control element, the disconnector operable to move in a first range of motion when the disconnector control element is in the first control position, and in a second range of motion when the disconnector control element is in the second control position.