In 1985 the 8 founding schools (known as the PAC-8) formed a league with the ideals of schools with similar-sized enrollments competing against one another.
The PAC-8 consisted of Lansdale Catholic (formerly of the Bicentennial League), Perkiomen Valley and Upper Perkiomen (from the Bux-Mont League), and 5 former Ches-Mont League schools - Phoenixville, Pottsgrove, Pottstown, Spring-Ford, and St. Pius X.
1988 brought two new members (both former Ches-Mont League schools) to the PAC, Great Valley and Owen J. Roberts to make the league a 10-member association, known commonly as the PAC-10. Boyertown was also made an associate member in the sport of Girls Lacrosse at this time.
In 2002 Boyertown gained full member status (formerly of the Berks County Interscholastic Athletic Association and Berks IC for football). They replaced Great Valley which left for the Southern Chester County League (later to merge with the Ches-Mont League).
In the Spring of 2007 Lansdale Catholic announced that the 2007-08 sports season would be its last in the PAC-10 as it accepted a membership into the Philadelphia Catholic League. To fill this void the league admitted Methacton (formerly of the Suburban One League) as a full member starting the Fall of 2008.
In May of 2009 the league approved the admission of Pope John Paul II High School. The new school is the result of a merger between charter member St. Pius X and Kennedy-Kenrick of Norristown. St. Pius X closed it's doors on June 11, 2010.
In February of 2015 the league approved Norristown (formerly of the Suburban One League) to become the 11th member of the league. Months later another Suburban One League team, Upper Merion, came to the PAC, increasing the theschool membership to 12 for the first time in league history.