The Catholic Youth Organization, or CYO, is a parish-based youth program that gives Catholic youth the opportunity to play various sports, participate in programs, and contribute to service projects within their community.  Stretching from Chester County, through Philadelphia and Delaware County, to Lower and Upper Bucks Counties, the CYO contains 14 Regions and over 150 Catholic elementary schools.

St. Mary's CYO competes primarily in Region 18 which includes St. Teresa Calcutta, St. Aloysius, Holy Family, and St. Basil.