Newcomer Abigail Lawrie stars as the troubled Krystal Weedon.
14 year old Sonny Serkis, son of actors Andy Serkis and Lorraine Ashbourne plays Paul Price with Joe Hurst as his older brother Arf.
As previously revealed on Screenterrier, the other young cast members include Simona (Chontelle) Brown as Gaia Bawden, Ria Choony as Sukhvinder Jawanda, and Brian Vernel as Stuart "Fats" Wall.
The all star adult cast includes Michael Gambon and Julia McKenzie as Howard and Shirley Mollison, Keeley Hawes as Samantha Mollison, Michelle Austin as Kay Bawden, Lolita Chakrabati as Parminder Jawanda, Monica Dolan as Tess Wall, and Rufus Jones as Miles Mollison.
The Casual Vacancy centres on Pagford, a seemingly idyllic English village with a cobbled market square and ancient abbey. Behind the pretty façade, however, is a town at war: rich at war with poor, teenagers at war with their parents, wives at war with their husbands, teachers at war with their pupils.
The BBC One miniseries, in association with HBO, is being produced by Bronte Film and Television, the independent production company run by JK Rowling and Neil Blair, from a script by Sarah Phelps.
The Casual Vacancy is due to air in 2015 on BBC One in the UK and on HBO in the US.