The Campeonato Nacional de Juniores is the top level of the Portuguese football league system for youth players (19-year-old and under).

The league started in 1938 and has been historically dominated by the Big Three clubs, with Benfica having the most titles won (25).

The Campeonato Nacional de Juniores begins in the first weekend of September and ends in June.

The Nacional de Juniors season is similar to the senior players' Primeira Liga playing a double round-robin points based system.

The top four teams with the most points in each group progress to the Apuramento de Campeão, where they face each other in a similar way to the first round, to determine the champion.