The 2011–12 Serie B (known as the Serie bwin for sponsorship reasons) will be the eightieth season since its establishment in 1929. A total of 22 teams will contest the league: 15 of which returning from the 2010–11 season, four of which promoted from Lega Pro Prima Divisione, and three relegated from Serie A. It began on 27 August 2011 and will end on 27 May 2012.