It is an eight-team league that plays a 42-game schedule and is overseen by the Royal Netherlands Baseball and Softball Federation (KNBSB).

The Eerste Klasse served as the top baseball competition in the Netherlands from its establishment in 1922 until 1957, excluding 1945 when play was suspended due to World War II.

[1] In 2021, the Eerste Klasse was reinstated as the second level of Dutch professional baseball and the league to which teams from the Hoofdklasse are relegated at the end of the season.

Following the 2021 season, the KNBSB decided to end relegation and promotion and operate the Hoofdklasse with fixed teams.

The reform was part of broader efforts to improve the league's quality of play and national visibility.