In the United Kingdom, European badgers Meles meles are a protected species and an important wildlife reservoir of bovine tuberculosis. We conducted a survey of badger dens (main setts) in 1614 1 km squares across England and Wales, between November 2011 and March 2013. Using main setts as a proxy for badger social groups, the estimated mean density of badger social groups in England and Wales was 0.485 km(-2) (95% confidence interval 0.449-0.521) and the estimated abundance of social groups was 71,600 (66,400-76,900). In the 25 years since the first survey in 1985-88, the annual rate of increase in the estimated number of badger social groups was 2.6% (2.2-2.9%), equating to an 88% (70-105%) increase across England and Wales. In England, we estimate there has been an increase of 103% (83-123%) in badger social groups, while in Wales there has been little change (-25 to +49%).