The Campeonato Nacional (English: National Championship) is the top tier league of the Chilean football league system. It is organized by the ANFP (English: National Association of Professional Football) and is ranked 25th in the IFFHS’ Best Leagues of the World ranking as of 2014. In 2015, the league became known as the Campeonato Scotiabank for sponsorship reasons.

Resembling the competition system in most Latin American countries (such as Argentina and Mexico), the Chilean First Division is currently played by 18 teams, which play two single-round tournaments per season, with the two tournaments known as Apertura and Clausura. Chile has used this format for most of the 21st century.

From 2002 to 2012, except in 2010, a system similar to that used in Mexico was employed. The Apertura tournament was played in the first half of the calendar year (usually held between January and June), followed by the Clausura tournament (between July and December). For each Apertura and Clausura tournament, a single round-robin tournament, called the regular phase, was played first. Afterwards, a post-season play-off began, where the best eight teams in each single-round tournament eliminated each other in the knockout tournament format in two-leg aggregate score. In the 2010 season, only one championship was held due to the devastating earthquake that hit the country that February.

In 2013, Chile changed to a season spanning two calendar years. As a result, a transitional 2013 season was held in the first half of the calendar year, with only one championship awarded. With the new format beginning in 2013–14, the Apertura is now contested in the second half of the calendar year, with the Clausura following in the first half of the next calendar year. The new format retains the single round-robin schedule of the recent past, but has no play-offs; this resembles the current Argentine season structure.

The Chilean League of Football has never been regular in terms of their tournament systems. Traditionally, the League had consisted in one annual, double round-robin tournament, with the addition of a Cup, but the number of contesting teams and League format has varied throughout the years, until the adoption of the Mexican system in 2002.

Relegation and promotion

Very much like the tournament format, the relegation/promotion (to Primera B) has changed throughout the years.

Currently, the two teams with the worst scores in the complete season (including Apertura and Clausura, but excluding the play-off stage), are relegated to Primera B, and replaced by the Champions and Runners-up of this Division. There is also a Relegation Playoff Tournament, played in a home-and-away basis by the teams that finish 15º and 16° in the First Division against the teams that finish 3° and 4° in the Primera B.

Qualification for international competitions

The champions of the Apertura and Clausura of each season are immediately qualified to Copa Libertadores for the next year. The third Chilean spot in that tournament is used by the team with the highest score in the Clausura regular phase (that is, excluding the play-offs).

For the Copa Sudamericana, the qualification system changes every year. As a sample, for the 2007 season, a small tournament was played by the top four teams in the Apertura. The winners of that tournament (Colo-Colo and Audax Italiano) qualified for Copa Sudamericana 2007.