Idrottsforeningen Elfsborg, more commonly known as IF Elfsborg or simply Elfsborg (Swedish pronunciation: [ˈɛ̌lfsbɔrj]), is a professional football club based in Boras, Sweden, and is affiliated to the Vastergotlands Fotbollforbund. They play in the Allsvenskan and have spent most of their history in the top tier of Swedish football. Their homeground is Boras Arena, where they have played since 17 April 2005.
The club was founded in 1904 by a group of 19 youngsters which all were 14–15 years old. Boras Fotbollslag was formed in Ordenshuset at Landala (today Knalleland) on 26 June 1904. The main protagonist in the formation, Carl Larson, who in addition to football also practiced athletics and wrestling. Claimed the reason was that the main sports club in the city, Boras Athletic and Sports Society, would not exert football in their program.
Carl Larson, however, found that there were too many clubs containing the city name Boras which contributed to the name change in 1906 by Riksidrottsforbundet to the current, IF Elfsborg.