Geldermalsen ( pronunciation ) is a municipality and a town in the western Netherlands. The municipality of Geldermalsen was formed on the 1 January 1978 when former municipalities Beesd, Buurmalsen, Deil and Geldermalsen were joined. The new municipality with an area of 101.73 km² (39.28 sq mi) is one of the largest municipalities in the Western Betuwe.