LSK's first major achievements on the national stage would come in the 1950s, after the club secured promotion to the newly established "Main League" in 1952.
This was largely due to a new generation of players coming through the academy, spearheaded by the talented striker Tom Lund.
[5] The 1977 season would be the biggest in the clubs history, when winning the double while facing Dutch giants Ajax in Lillestrøms first ever European Cup-game.
This fixture held extra symbolism, as Tom Lund had declined an offer from Ajax in 1973, while still playing in the Norwegian Third division.
During the rest of the 1990s, the club would be an established force in the upper half of the league, and was occasionally close to challenging Rosenborg for the titles.
2001 would be the closest the club got to regaining their league title, when at the final day of the season, Lillestrøm remained only one point behind.
While Lillestrøm made a promising start, being 2–0 ahead at half-time, what followed was a parachutist flying through the roof over the singing supporters.
Big economic issues lead to weaker results on the pitch,[10] and the club remained almost exclusively in the lower half of the table until eventually getting relegated after a playoff game against Start in 2019.