The Norwegian First Division (Norwegian: 1. divisjon) is the second highest division of the Norwegian football league system. The league was established in 1948 following a reorganization of the Norwegian league system. Reducing number of teams in the top level from 74 to only 16. The first season had 83 teams divided on 11 regional departments. In 1951 the league was reorganized into 54 teams divided on 7 regional groups. And renamed to Landsdelsserien (English: The Regional series). Another reorganization came in 1963. Reducing number of teams to 16 divided on two groups. And the league was renamed to 2. divisjon (Norwegian: Second Division), a name that has later been used for the third level league from 1991. In 1970 teams from Northern Norway was allowed into the league. And the total number of teams was increased to 30 teams divided on four groups. Which later was expanded to 35 teams in 1972, and then 36 teams in 1973. This was then reduced to 28 teams divided on 3 groups in 1976. But then expanded to 30 teams in 1977. A final structure came in 1979. With a reduction to 24 teams divided on two groups. Following the name change of the top league from 1. divisjon to Tippeligaen ahead of the 1990 season. The league inherited the name 1. divisjon the season after. In 1997 the two groups were merged and number of teams was reduced from 24 to 14. This lasted for four season until the latest change came in 2001. When number of teams were expanded to 16. Ahead of the 2005 season, the league signed a sponsorship deal with Adecco. And the league was renamed Adeccoligaen. After the 2013 season, the sponsorship with Adecco expired. And the league was again renamed back to its former name, 1. divisjon.
Formally, Adeccoligaen was a semi-professional league.
In 2009, the number of teams in the Norwegian Premier League expanded from fourteen to sixteen. Therefore, 2008 was a transitional season, in which more teams were promoted to the top flight, and fewer teams relegated to the Norwegian Second Division, than usual.
From 2009, the First Division winners and runners-up earn automatic promotion. A new playoff system was introduced, involving the teams finishing third, fourth and fifth in the First Division, and the team finishing third from the bottom in Tippeligaen. Teams three and four would play against each other, and face the winner of team five versus team fourteen from Tippeligaen. Promotion is awarded to the winning team. The four teams finishing at the bottom of the after ended season will be relegated to the Second Division.
As of 2014, C More and TV 2 Zebra owns the broadcasting rights. C More and TV 2 Zebra broadcast one match each every round. C More usually on Saturdays, and TV 2 Zebra usually on Mondays. The remaining six matches each round are usually played on Sundays. And are available for streaming on C More's web-TV service, C Sports.