Mueni Mulandi, 16, has not been seen since 10.30pm on Monday 5 August 2013, at her home on St George’s Road, Harrogate.
She is described as black, 5ft 1in and of medium build. She has a fresh complexion, brown eyes and black shoulder-length hair.
Police are growing concerned for Mueni’s welfare due to her age and the time she has been missing.
Although her whereabouts are unknown, police enquiries indicate that Mueni may be in the Aberdeen area of Scotland.
Inspector Jon Naughton, of Harrogate Safer Neighbourhood Team, said:
Mueni, if you see or hear this appeal, I urge you to make contact with your family, friends or police straight away. We are all worried about you and want to know that you are safe and well.
I am also asking anyone who has seen Mueni since she went missing or may have spoke to her in the last few days and ask them to get in touch.
Anyone who can help to locate Mueni is asked to contact North Yorkshire Police on 101, select option 2 and pass the information to the Force Control Room.