The Leinster Schools Junior Cup competition is confined to students under the age of 16.

[citation needed] Castleknock College dominated the competition in the 1920s, winning 6 titles including their three-in-a-row (1920–1922).

These are Blackrock, who have achieved this feat 26 times (1910, 1912, 1927, 1933, 1935–36, 1942–43, 1945, 1948, 1953–54, 1956–57, 1962, 1964, 1981–82, 1986–87, 1995, 2004, 2006, 2013–14, 2018), St Michaels twice (2012 and 2019), Newbridge College (2020), Belvedere (2005), Terenure (1958) and Castleknock (1920).

Since the Junior Cup records began, only the decade of the 1970s did not produce a double.

[citation needed] During the 16 years from 1975 to 1990 the Junior Cup was won by only three different schools.

[citation needed] In the 1977 JCT Final at Lansdowne Road, Terenure were trailing Blackrock by 10 points to 9 points at the end of full time when they were awarded a penalty inside their own half, directly in front of the posts.

Cistercian College Roscrea made their first Junior Cup Final in 82 years (last appearance was 1940).

[3] SCT & JCT Double 26 times – 1910, 1912, 1927, 1933, 1935, 1936, 1942, 1943, 1945, 1948, 1953, 1954, 1956, 1957, 1962, 1964, 1981, 1982, 1986, 1987, 1995, 2004, 2006, 2013, 2014, 2018 Note: This list is based on the information below which may be incomplete.