The United States Junior Amateur Championship is one of the thirteen U.S. national golf championships organized by the United States Golf Association. It is open to amateur boys who are under 18 on the last day of the competition and have a USGA Handicap Index of 6.4 or less. The competition was established in 1948. It consists of two days of stroke play, with the leading 64 competitors then playing a match play competition to decide the champion.

The first tournament in 1948 was won by Dean Lind from a field of 495 enties. In 1999, the tournament set a record with 4,508 entries.

Tiger Woods, who won the tournament in 1991, 1992, and 1993, is the only player to have won the Junior Amateur more than once. Woods, who was 15 years and 220 days old when he won in 1991, remains the youngest champion, although the 2004 champion Sihwan Kim was only 22 days older, and his defeated final opponent David Chung was just fourteen and six months. The number of winners who have gone on to become leading professionals is quite modest. This reflects not only the young age of the competitors, but the more random results of match play tournaments compared to stroke play events. Apart from Woods, well known winners include Johnny Miller (1964) and David Duval (1989). Jack Nicklaus's best result was a semifinal loss.