2018 1. divisjon

The 2018 OBOS-ligaen is Norway's second-tier football league.

The season began on 2 April 2018 and is scheduled to end on 11 November 2018.

Team changes
The following teams have changed division since the 2017 season.

To OBOS-ligaen
Promoted from 2. divisjon
 * HamKam
 * Nest-Sotra
 * Notodden

Relegated from Eliteserien
 * Sogndal
 * Aalesund
 * Viking

From OBOS-ligaen
Promoted to Eliteserien
 * Bodø/Glimt
 * Start
 * Ranheim

Relegated to 2. divisjon
 * Fredrikstad
 * Elverum
 * Arendal

Promotion play-offs
The third to sixth-placed teams will take part in the promotion play-offs; these are single leg knockout matches, two semi-finals and a final. The winners will advance to play the 14th placed team in Eliteserien over two legs in the Eliteserien play-offs for a spot in the top-flight next season.

Relegation play-offs
The 14th placed team will take part in a two-legged play-off against the winners of the 2. divisjon play-offs to decide who will play in the 2019 OBOS-ligaen.