Allison Berger, 17, was last seen in the 4800 block of Radnor the afternoon of Aug. 23.
Berger's family told police she has a mental illness.
She is white with brown hair, is 5 feet, 7 inches tall, and weighs 125 pounds. She has several tattoos – three small black birds on the back of her neck, a colorful tree frog inside her arm, and a flower on her back.
Anyone with information about Berger's whereabouts is asked to contact Crime Stoppers at 1-800-SPEAK-UP.