Major League Baseball Players Alumni Association - Organization of former players. Features information, history, and news of the organization's activities. - http://www.mlb.com/mlb/features/alumni/
American Amateur Baseball Congress - Coordinates play among US leagues in seven age brackets, from sub-teens through adults. Includes rules, tournament dates, and list of regions and age divisions. - http://www.aabc.us/
Amateur Baseball Umpire Association - An umpire information center. Umpire associations, umpire equipment, umpire rules; a resource center for umpires to find and share information. - http://www.umpire.org/
American Federation of Umpires(AFU) - Group of baseball and softball umpires who share the common goal of consistent improvement in their officiating skills and knowledge of the game. Features clinics, a newsletter, and various resources. - http://www.americanfederationofumpires.com/
The United States Amateur Baseball Association. - The USABA is here for the promotion and development of the players and fans in youth baseball pastseason tournament competitions at state, regional, and national level. - http://www.usaba.com/
American Baseball Coaches Association (ABCA) - A nonprofit organization having more than 5,000 members, including coaches from every state in the country and over 200 international members. - http://www.abca.org/