The Amateur Softball Association (ASA) is a national organization in the United States that provides support services to softball leagues. ASA has resources for youth leagues and traveling teams, as well as adult recreational leagues and competitive adult programs. The ASA rule book outlines pitching rules for regular season leagues and tournament play for all ages and ability levels.
Fast Pitch
The pitcher in fast pitch softball must stay off the pitching rubber until she has the ball in her hand. She is not considered to be in an eligible pitching position until the catcher is in place behind home plate. Once those things happen, the pitcher takes position on the slab. Under ASA rules, girls and women's league pitchers must start with both feet on the rubber, while boys and men's fast pitch players need only have the pivot foot on the rubber while the other foot can be behind it. The pitching motion must be forward and continuous, and the ball has to be released from a spot lower than the hip. The fast pitch pitcher is prohibited from wearing wristbands or bands around other parts of the arms or legs that might distract the batter. The umpire decides what items fit that description.
Slow Pitch
The slow pitch pitching motion in ASA softball starts in the same way as the fast pitch delivery, with at least one foot on the pitching rubber. The pitch release point must come from lower than the hip, and the motion must be continuous. The pitcher in slow pitch softball is allowed to step forward, sideways or even backward as he delivers the ball, but the arm must continue forward. The pitch must reach an arc of at least 6 feet in height but must not arc higher than 12 feet or it will be called an illegal pitch by the umpire. If the batter swings at an illegal pitch, it is in play, but if she does not swing, it is a ball.
Placement of the Pitching Rubber
The pitching rubber in adult fast pitch softball is situated 43 feet away from home plate for women's play and 46 feet for the men. ASA adult slow pitch leagues play on a field with the pitching rubber a full 50 feet away from the plate.
ASA youth fast pitch rules start the youngest pitchers--those age 10 and under--on a pitching rubber that is 35 feet away from home plate. Girls then move to 40 feet up to age 18. Boys' rules move the pitching rubber back to 40 feet for their 11- and 12-year-old seasons before moving to 45 feet. Youth slow pitch starts pitchers at 40 feet for 10 and under, then slides back to 46 feet for 12 and under before reaching 50 feet for the upper-age levels.