A or single A is the third level of the minor leagues and has in recent decades comprised multiple levels of play: A-Advanced (ex. Carolina League), lower full-season class A (ex. South Atlantic League) and A (short-season) (ex. New York-Penn League). The difference between the lowest class A and the highest is almost as large as the difference between AA and AAA; each league is made up of different types of players.
Single A leagues prior to the creation of the Professional Development League in 2021:
In 2021, the creation of the PDL reduced Class A to two levels: High-A and Low-A, with short-season A disappearing altogether. Today, class A is structured as follows:
- Lucas Mann: Class A: Baseball in the Middle of Everywhere, Pantheon Books, Random House, New York, NY, 2013. ISBN 978-0307907547