The St. Paul's School for Girls, also known as SPSG, adjoins the campus of the St. Paul's School on Falls Road but is a separate institution. The Gators of SPSG attend a small, independent day school educating over 400 girls in grades 5 through 12. Located on 38 acres in the Green Spring Valley of Baltimore County, Maryland, the school is committed to single-sex education for girls with a carefully structured leadership program for its students. The school's mission statement states that St. Paul's School for Girls educates the minds and hearts of girls in a supportive and intellectually challenging community that encourages respect, integrity, creativity, and spiritual growth, preparing them as independent and confident young women to embrace the extraordinary opportunities of our complex world.

Proud of its affiliation with the Episcopal Church through Old St. Paul's, the oldest Episcopal congregation in downtown Baltimore, the school endeavors to pass on the spiritual and ethical values of the Judeo-Christian heritage and to instill in each girl a sense of stewardship and service. SPSG strives to create an environment that is supportive of the multicultural fabric of the school and the Baltimore community. A state-designated Green School, SPSG supports initiatives to preserve and conserve environmental resources.