Sarah Murnaghan, who turned 11 on Aug. 7, was discharged from The Children's Hospital of Philadelphia and later was carried into her family's Newtown Square home, where the entrance was festooned with balloons and bore a big sign saying "Welcome Home, Sarah!"
Sarah received two sets of lungs this summer as she struggles with the effects of end-stage cystic fibrosis.
Her mother, Janet Murnaghan, said in a Facebook post late Monday that she and her daughter had "cried tears of joy."
"We entered CHOP on Feb. 19, more than six months ago. I never could have imagined the journey that lay in front of us," Murnaghan wrote in the post, thanking God, Sarah's donors and all those who supported the family. She said she plans to speak with reporters Tuesday afternoon.
Her release capped days of upbeat progress reports from the family.
On Sunday, Murnaghan said her daughter was taken off oxygen, although she still gets support from a machine that helps her to breathe, and had started to walk with the aid of a walker, even venturing outside.
Family spokeswoman Tracy Simon said Sarah's recovery is now focused on building her muscle strength so she no longer has to use a breathing tube. She said Sarah recovered from a case of pneumonia that stemmed from the tube.
Sarah's first set of adult lungs failed after a June 12 transplant. A second set was transplanted three days later.
She received the transplants after her parents went to federal court to challenge national transplant rules that put her at the end of the waiting list for adult lungs. A federal judge intervened, forcing the Organ Procurement and Transplantation Network — the private nonprofit group that manages U.S. organ allocation — to add Sarah to the adult list.
The case raised questions among some health specialists and medical ethicists about how organ donation rules are developed and under what circumstances they might be disregarded.
UNOS spokeswoman Anne Paschke said Tuesday that the temporary option for other children to apply for adult lungs will be in effect until the end of June 2014. She said a committee is currently studying whether to make that change permanent, or make other changes to adolescent lung transplant rules.
Paschke said two other children have received adult lung transplants as a result of the temporary rule.
Associated Press writer Kevin Begos in Pittsburgh contributed to this story.
Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.