[2] Scullion has helped to found a number of organizations to address homelessness in Philadelphia, including Project H.O.M.E., which focuses on affordable housing ("H"), opportunities for employment ("O"), medical care ("M"), and education ("E").

[8] Scullion attended Little Flower Catholic High School for Girls in Philadelphia, where she became aware of the work of the Sisters of Mercy.

The Sisters responded by setting up cots for the women at St. Rita’s, a local bingo hall, to give them a place to sleep.

[3] She was particularly inspired by the words of Dorothy Day, Mother Teresa, and Basque Jesuit priest Pedro Arrupe at the 41st International Eucharistic Congress, in Philadelphia in 1976.

[3] In 1978,[5] at her own request, Scullion spent a week-long mandatory yearly retreat living as a homeless woman on the streets of Philadelphia.

[11] Also in 1988, Scullion met Joan Dawson McConnon, then a student at Drexel University who volunteered at Mercy Hospice.

The move met with opposition from politicians including Vincent Fumo and then-Mayor Ed Rendell, resulting in a protracted court battle.

[16] Scullion's advocacy efforts led to a landmark federal court decision that affects the fair housing rights of persons with disabilities.

[26][27] She received the Judge Edward R. Becker Citizenship Award from the Center for Law and Society at the Community College of Philadelphia in 2009.

[11][30] In 2002 Scullion and Joan Dawson McConnon were national awardees of the Ford Foundation's prestigious "Leadership for a Changing World Award".

[32] In 2009, Scullion was named by TIME as one of the year's "100 Most Influential People in the World", alongside Michelle Obama and Oprah Winfrey.

[1] In 2011, Scullion and McConnon received the Laetare Medal from the University of Notre Dame, the highest award given to an American Catholic.