The cantera (quarry) of Spanish professional football club Athletic Bilbao is the organisation's youth academy, developing players from childhood through to the integration of the best prospects into the adult teams.

[11][7][8] Including eight former trainees at other eligible clubs, Athletic's total of 25 homegrown players ranked as the fifth-highest across the continent, although only third in Spain behind Real Madrid and FC Barcelona who retained just a few of the many high-level professionals they produced.

[6] The players who are retained by Athletic after their Juvenil A spell (aged about 18) typically join the club's farm team in Basauri, CD Basconia, playing at the regionalised fourth level of the Spanish adult system.

Their squad is normally expanded further with new signings from the wider regions's youth clubs,[13] most notably Danok Bat[14][15][16] and Antiguoko[17] who regularly challenge the professional academy teams for the title in their División de Honor group.

[3] There are exceptions to this sequence; notably Iker Muniain showed such promise that he was promoted early to Juvenil A as a 15-year-old in 2008, was selected by Bilbao Athletic as soon as he turned 16 in January 2009 and became a senior team regular at the start of the next season.

The alternative route into the Youth League would be to win the previous season's Copa de Campeones but Athletic Juvenil have so far been unable to achieve this – they were losing finalists in 2022.

In 2006 (featuring Erik Morán in the squad) and 2012 (including Asier Villalibre) Athletic cadets also competed at the Manchester United Premier Cup world finals as the Spanish league representative after winning the national qualifier.