What must a fast pitch pitcher do to deliver a legal pitch?

Under WBSC rule 4.3 (2026-2029), before the pitch:

• All players are in fair territory and the catcher is in the catcher's box ready to receive the pitch.
• The pitcher has the ball and the pivot foot in contact with the pitcher's plate, with both feet within the 61.0 cm (24 in.) length of the plate and the hips in line with first and third bases.
• The pitcher takes, or appears to take, a signal from the catcher with the hands separated.
• After the signal, the pitcher comes to a full stop with the ball in both hands in front of the body (holding it in both hands to the side counts as in front), non-pivot foot stationary. That position is held for not less than 2 and not more than 5 seconds before release.

During the delivery:

• The pivot foot must stay in contact with the plate before the pitch starts. Lifting it off the plate and returning it, or creating a rocking motion, is an illegal act.
• One revolution only on the windmill, an underhand motion with the hand below the hip and the wrist not further from the body than the elbow, and no stop or reversal of the forward motion.
• One step only with the non-pivot foot, simultaneous with release, forward toward home plate and within the length of the plate.
• No crow hop, and the ball must not be deliberately dropped, rolled or bounced to stop the batter hitting it.
• The pitcher has 20 seconds to release the next pitch after receiving the ball or after the umpire says "Play ball".

After taking the pitching position, the pitcher may not throw or fake a throw to a base during a live ball with the foot in contact with the plate. The pitcher may disengage only by stepping backward off the plate before separating the hands.