In baseball, an uncaught third strike (often inaccurately referred to as a dropped third strike) occurs when the catcher fails to cleanly catch a pitch for the third strike. A pitch is considered uncaught if the ball touches the ground before being caught, or if the ball is dropped after being grasped (see also catch). In Major League Baseball, the specific rules concerning the uncaught third strike are addressed in Rules 6.05 and 6.09 of the Official Baseball Rules.
On an uncaught third strike with no runner on first base or with two outs, the batter immediately becomes a runner. The strike is called, but the umpire does not call the batter out. The umpire may also actively signal that there is "no catch" of the pitch. The batter may then attempt to reach first base and must be tagged or thrown out. With two outs and the bases loaded, the catcher who fails to catch the third strike may, upon picking up the ball, step on home plate for a force-out or make a throw to any other fielder.
One intent of this rule is to ensure that a defensive player fields the ball cleanly in order for that team to record an out. It was thought that it was not enough that the offensive player be unsuccessful at the plate in order for an out to be made; a defensive player must be successful as well.
Regardless of the outcome of an uncaught third strike, the pitcher is statistically credited with a strikeout. Because of the uncaught third strike rule, it is possible for a pitcher to register more than three strikeouts in an inning, a feat which has been accomplished in Major League Baseball 56 times.
If at the time of the strike three pitch, first base is occupied with fewer than two outs, the batter is automatically out and cannot become a runner. This is to prevent the defense from deliberately dropping a third strike pitch and getting a double or triple play as a result, because of the possible force play at second, third base, or home plate in this situation.
In Little League divisions Tee-Ball, Minor League, and Little League (or the Major Division) the batter is out after the third strike regardless of whether the pitched ball is caught cleanly by the catcher. In Junior, Senior, and Big League divisions a batter may attempt to advance to first base on an uncaught third strike. Little League Major Division Softball as well as many other youth baseball leagues, such as the USSSA also follow the rule.