EMASS has two leagues and players can participate in one or both of them. The number of teams in each league is subject to seasonal changes depending upon the number of players registered.

• The Saturday league is divided into two divisions. In 2009, the American Division has 5 teams and the National Division has 9 teams. Most games are played on Saturday mornings at various fields, such as Wayland, Peabody, Canton, or Cambridge. Both Saturday league divisions have paid umpires and playoffs.
  
• In 2009 the Atlantic Division has nine teams. Games are played in Wayland and Waltham on Tuesday mornings.

The Saturday league, especially the American Division, is somewhat more competitive, as it has a higher percentage of younger players than either the Atlantic Division (in which most players are retired) or the National Division of the Saturday league.
In 2008, EMASS opened its doors to 50-54 year olds who would like to join the American Division. Each American Division team was allowed to have a limited number (2) of 50-54 year old players on their roster. In 2009, EMASS plans a trial in which it will allow 50-54 year olds to play in the National Division if they do not qualify for the American Division.

The season for both leagues starts the first week in May and ends the last week in August. Thus, each team will play a schedule of about 30 games.

For those who want to play even more there are tournaments and informal games, particularly in the fall. EMASS is led by a commissioner and a 12-member board of directors, all of whom are elected by the players.