Superior umpiring requires complete competence of the two-umpire system. This system serves as the fundamental building block upon which the three-, four-, and even six-umpire systems are developed. This manual has accordingly been prepared by the Professional Baseball Umpire Corp. as a reference and guide for umpires working in the Minor Leagues when working a two-umpire system. Its concepts and methods are those taught at the Professional Umpire Schools and at the Professional Baseball Umpire Evaluation Program for candidates seeking umpiring positions in the Minor Leagues.