Beaucroissant is located some 32 km south by south-east of Bourgoin-Jallieu and 25 km north-west of Grenoble. Access to the commune is by the D1085 road from La Frette in the north-west which passes through the commune just north of the village and continues east to Moirans. The D519 comes from Izeaux in the west and passes through the commune turning north to join the A48 autoroute at Exit 9 . A railway from Le Grand-Lemps passes through the commune with a station in the village and continues north-east to Rives. Apart from the village there is the hamlet of Le Mollard. Apart from the large urban area of the village and Le Mollard the commune is mainly farmland.
The commune is famous for its annual fair which has continued since 1219 due to the pilgrimage of Our Lady of Parménie. The history of the village and the Fair is linked with the Parménie hill that dominates the commune with its 749-metre altitude.
The origin of the Beaucroissant fair dates back to 14 September 1219 when the Saint Laurent lake (above the Bourg d'Oisans) overflowed causing a terrible flood that inundated Grenoble and had many victims. Starting from 14 September 1220, organised by the bishop of Grenoble, survivors commemorated this event with a pilgrimage to Parménie. They were so numerous that a village was needed to accommodate them. The assembly attracted many merchants so the Fair of Beaucroissant was begun.
In 2012 the commune had 1,522 inhabitants. The evolution of the number of inhabitants is known from the population censuses conducted in the commune since 1793. From the 21st century, a census of communes with fewer than 10,000 inhabitants is held every five years, unlike larger communes that have a sample survey every year.[Note 1]
The Beaucroissant Fair, which takes place twice a year, is the main economy of the commune. In 2015 it took place on 25 and 26 April and on 11, 12, and 13 September together with the cattle fair on Friday 11 September.
^At the beginning of the 21st century, the methods of identification have been modified by Law No. 2002-276 of 27 February 2002, the so-called "law of local democracy" and in particular Title V "census operations" allows, after a transitional period running from 2004 to 2008, the annual publication of the legal population of the different French administrative districts. For communes with a population greater than 10,000 inhabitants, a sample survey is conducted annually and the entire territory of these communes is taken into account at the end of the period of five years. The first "legal population" after 1999 under this new law came into force on 1 January 2009 and was based on the census of 2006.