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.

National Adult Baseball Association - NABA amateur baseball organization information, including tournament results, events and how to join.

Over 50 Baseball - Promoting an affordable week-long fantasy-camp type fun tournament in Las Vegas each October. Also promoting the establishment of local leagues nationwide.

Roy Hobbs Adult Baseball - Amateur baseball organization for adults over the age of 28.

Team One Baseball - Scouts baseball's high school, college and minor league players and compiles information on the annual Baseball Draft.

Vintage Base Ball Association - Listing of rules, tournaments, members and contact information.