Built upon shared values and historic rivalries, the Founders League was established in 1984, by heads of school who sought to create shared athletic philosophies and practices for their highly selective college preparatory schools. Put simply, the goal of the founding heads of school was to create a league that encouraged educational excellence, sportsmanship, and outstanding competition. Since its inception, the League has been recognized for its ability to promote the highest level of athletic competition, in a manner consistent with the educational philosophies and integrity that are hallmarks of its constituents. Today, the Founders League is one of the most competitive and respected athletic leagues in the country. 

The membership of the Founder's League has remained largely unchanged over the years, and today, as was the case in 1984, the League is comprised of the following eleven schools: Avon Old Farms, Choate Rosemary Hall, Ethel Walker School, The Hotchkiss School, Kent School, Kingswood Oxford School, Loomis Chaffee, Miss Porter's School, The Taft School, Trinity-Pawling School, and Westminster School.

The Founders League is recognized by the New England Preparatory School Athletic Council. Founders League competition takes place in the following sports: baseball, basketball, cross country, field hockey, football, golf, ice hockey, lacrosse, soccer, softball, squash, swimming, tennis, track and field, volleyball, and wrestling. By and large, member schools compete for the Founders League Championship in each of the aforementioned sports for which a team is fielded. In some cases, Founders League teams collectively participate in regional leagues or tournaments, including the New Englands.  Even when competing outside the Founders League, member schools strive to adhere to the League's ideals.

To ensure continued alignment between the League's athletic mission and its member schools' educational philosophies, the Founders League is run collaboratively by the heads of school from each member institution, with the assistance and counsel of the athletic directors. This structure also serves to foster collegiality between member schools.