2008 Official Rules of Major League Baseball, $9.95 sold by Amazon.com
The starting point for baseball umpire study material is the Official Rules of Major League Baseball. These are the rules set forth by Major League baseball governing the playing of baseball games by professional teams of Major League Baseball and the leagues that are members of the National Association of Professional Baseball Leagues. It is also used by many amateur leagues. Baseball rules have been around since before the 1850's and the National League Rules were promulgated in 1877. Today the Official Rules of Major League baseball (or OBR as umpires refer to it) is well over 200 pages.
Knowing the OBR rules is one thing. Understanding the rules is something different. The following publications aid in the study and understanding of the baseball rules:
PBUC Umpire Manual, $14.95 sold by Jim Evan's Umpire Academy
This umpire manual is endorsed by Minor League Baseball and the Professional Baseball Umpire Corp. (PBUC). It contains contains interpretations, clarifications, general practices, and rulings and is a supplement to the Official Baseball Playing Rules which govern all games in Minor League Baseball.
Jaksa Roder Manual, $39.99
The Rules of Professional Baseball: A Comprehensive Reorganization and Clarification by Chris Jaska and Rick Roder. The J/R Manual is a complete rewrite of Baseball's Official Rules and includes MLB and PBUC interpretations as well as NCAA, NAIA, and NFHS rule differences. While not an authorized by any league, it is endorsed by many professional umpires and is considered an essential publication for understanding the rules of baseball.
Baseball Rules Differences
The BRD by Carl Childress offers information and comparison on the NFHS (high school), NCAA and NAIA (college), and the Official Baseball Rules. For umpires that work with these different rules this book is terrific!
For college play the CCA Umpire's Manual provides necessary information on mechanics and techniques. For NCAA rules, the Study Guide: College Baseball Rules is a great resource with easy to read analysis of the NCAA rules.
High School Baseball Rules: Simplified and Illustrated is designed to help you visualize the NFHS rules through the use of illustrations.
Manual For The Two-Umpire System $14.95, sold by Jim Evan's Umpire Academy
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.