The IAAF World U18 Championships (formerly named the IAAF World Youth Championships in Athletics up to November 2015) is a global athletics event comprising track and field events for competitors who are 17 or younger (youth). The event is organized by International Association of Athletics Federations (IAAF). It is held biennially. It was first held in 1999.
The World U18 Championships are not to be confused with the World U20 Championships, which are for athletes who are 19 or under.
In the 206th IAAF Council Meeting, held after the 2016 Summer Olympics, the council decided to conclude the world championship for under-18 athletes after the 2017 event. The decision was made with the intention of improving under-18 competitions at continental level instead.