Daniel Devaney was last seen when he left his home in Terenure at around 8:30am yesterday morning.
The 15-year-old went missing on his way to school.
He's around 6'3" in height, of medium build, with green eyes and blonde hair.
When last seen, he was wearing his school uniform - navy trousers, a navy/blue school jumper, a light blue rain jacket and a black backpack.
Anyone who can help to find Daniel is being asked to contact Gardai.