Reece Chubb, 16, went missing from a home in Bolton at around 10.45am on June 17.
He is described as 5ft 8in tall, with blonde/light brown hair and wears glasses. He was last seen wearing grey Nike tracksuit bottoms and a black jacket.
Police are very concerned for Reece’s welfare and are urging anyone who knows where he is to come forward.
Temp Det Sgt Joanne Duncan, of Lancashire Police, said: "Reece has been missing for some time now and this is of serious concern to us.
"We are appealing to anyone who has seen him or knows where he is.
"I would also urge Reece, if he sees this appeal, to come forward and speak to us and let us know he is safe."
Anyone with information can contact police on 01524 596627 or email [email protected] In an emergency always call 999.