Born and raised in Glenside, Pennsylvania, to Bob and Mary Dean, Madeleine got her start in politics around the dinner table with her five older brothers and one older sister. She was graduated from Abington High School, and at age 18 won election to serve as a local committee-person.

Madeleine completed her undergraduate studies at La Salle University in Philadelphia, and earned her law degree at Delaware Law School of Widener University. She returned home, practicing law in a small Philadelphia firm and with the Philadelphia Trial Lawyers Association and eventually serving as executive director. Madeleine then opened a small, three-woman law practice in Glenside.