Tatiana Isabel Sanchez walked out of her group home in the Pierrefonds-Roxboro borough at about 8:30 p.m. on Jan. 30 and has not been seen since.
Pina Arcamone, director of the the Missing Children's Network, said they are especially concerned about Sanchez because she is so young.
"She's only 13-years-old ... that makes her extremely, extremely vulnerable to predators that you know may be preying upon young children."
Sanchez was wearing a short black coat, a pink and black hoodie, and pink leggings when she was last seen.
Police are asking for anyone with information on the missing girl to phone Info Crime at 514 393-1133.