Mjøndalen is a small industrial town 11 km west of Drammen on the south side of Drammenselva. The name comes from Old Norse meaning "mill valley". The economy was traditionally based on timber, paper and textiles.
The town is best known for its football club Mjøndalen IF, founded 1910, who play in distinctive brown and yellow. They won the Norwegian Cup three times in the 1930s and have twice finished second in the top league. Their 4,350-capacity Consto Arena still draws loyal crowds. The club also has a successful bandy section with 14 national championships.
The poet Herman Wildenvey grew up at farm Portåsen here. A statue by Ørnulf Bast stands in the town park. The 1910 Mjøndalsbrua bridge, originally built for horse-drawn carriages, connects to Krokstadelva on the opposite bank.