It happened on the 2400 block of North 19th Street on Saturday.
According to police, the child was playing on the window sill when she fell.
She suffered a head injury and injuries to her arm and leg. She was taken to Children's Hospital of Philadelphia for treatment.
A neighbor says she notified the victim's mother that the child had fallen out of the window.
The mother thought, "It was the air conditioner that fell out of the window, but it was the child," said neighbor Tasha.
The incident is under investigation.