Haverford is a member of the historic Inter-Academic Athletic League, or Inter-Ac, formed in 1887 as the Inter-Academic Athletic Association. The Inter-Ac is the country's oldest inter-scholastic athletic conference and was expanded in 2013 to include girls' sports. The league consists of The Haverford School, The Agnes Irwin School, The Baldwin School, The Episcopal Academy, Germantown Academy, Malvern Preparatory School, The Academy of Notre Dame de Namur, Springside Chestnut Hill Academy, and William Penn Charter School.
Haverford fields 17 interscholastic sports. In 2016, the football, lacrosse, soccer, squash, and tennis teams were Inter-Ac League Champions. In the past decade, Haverford has won championships in cross-country, soccer, football, squash, hockey, lacrosse, baseball, tennis, crew, wrestling, and golf.
In 2011, the varsity lacrosse team achieved a perfect 23-0 season, ranking No. 1 overall in the nation, and repeated this achievement in 2015 with a 26-0 record. The varsity tennis team achieved perfect seasons in 2012 and 2013, earned the Inter-Ac League title for the seventh consecutive year in 2016, and ranked 6th in the nation in 2015.
The Fords have won The Heyward Cup, awarded each year to the Inter-Ac school with the best overall league record, 16 times – more than any other Inter-Ac school – including 1975, 1976, 1977, 1978, 1980, 1989, 1994, 2000, 2005, 2006, 2009, 2010, 2011, 2013, 2015, and 2016.