Derbyshire Building Society (previously trading as The Derbyshire) was a UK building society based in Duffield, Derbyshire in the East Midlands of England. It was the 9th largest building society in the United Kingdom based on total assets of £7.1 billion at 31 December 2007, until it was acquired by Nationwide Building Society on 1 December 2008. It operated as a trading division of the society, with 50 branches, until it was fully integrated into its parent in November 2014.