The last confirmed sighting of 16 year-old Bailey Townend was in Harrogate at around 10.15pm on Wednesday 17 April 2019.
Despite extensive enquiries since then, officers have been unable to locate Bailey and are growing increasingly concerned for his welfare.
They are now appealing to the public for information as to his whereabouts.
Bailey is described as white; around 5ft 6ins tall, of average build, and has brown hair and blue eyes.
It is believed that he could still be in the Harrogate area.
If you think you might have seen Bailey, or have any information, please contact North Yorkshire Police on 101 and pass information to the Force Control Room.
If you have an immediate sighting of him, please call 999.