Harley Anderton, 14, Kye Hollingworth, 13, and Logan Gray, nine, were reported missing from Witherslack in Cumbria on March 15.
Police believe the three young boys are together.
The force said they were “concerned for the welfare of three young people missing from Witherslack.”
Harley is described as being 5ft 6 inches tall, of slim build and has short brown hair.
It is believed he may be wearing a green jumper, black trousers and black trainers.
Kye is described as being 6ft tall, large build and has short black curly hair.
He is thought to be wearing a black zip-up hoodie, a blue T-shirt, black shorts and black trainers.
Logan is described as being 4ft tall, of slim build and has short brown hair.
Police said they think he may be wearing a grey jumper, white polo shirt, black trousers and black trainers.
Officers are appealing for anyone who has information on their whereabouts to contact police.
Anyone with information can report online at www.cumbria.police.uk/report-it or call police on 101, quoting incident number 117 of March 15.
