As mentioned, Riot Fest is taking place in Humboldt Park and at the Congress Theater, who host the opening night, from September 14-16. Two-day passes and single-day tickets are still available. (Avoid service charges by purchasing passes at The Music Garage and/or The Alley).

They've also just announced a few festival aftershows. Here's a full list of them:

Friday, September 14
Alkaline Trio, Brendan Kelly @ Empty Bottle
Naked Raygun, Dan Vapid & The Cheats @ Subterranean
Frank Turner @ Cobra Lounge

Saturday, September 15
NOFX, The Casualties, The Adicts, The Dickies @ Congress Theater
Fishbone @ Cobra Lounge

Advance tickets for all aftershows are on sale now.

Full festival lineup-by-day is below...

Riot Fest -- 2012 Lineup
Friday, September 14 @ Congress Theater
The Offspring
Neon Trees
Dead Sara
Saturday, September 15 @ Humboldt Park
Rise Against
Coheed and Cambria
Dropkick Murphys
The Gaslight Anthem
Andrew W.K.
Hot Water Music
Minus the Bear
August Burns Red
Frank Turner
The Adicts
A Wilhelm Scream
Teenage Bottlerocket
Off With Their Heads
Deals Gone Bad
Larry And His Flask
The Story So Far
Environmental Encroachment
Of Mice & Men

+ more TBA
Sunday, September 16 @ Humboldt Park
Iggy And The Stooges
Elvis Costello & The Imposters
A Day to Remember
Gogol Bordello
Alkaline Trio
The Jesus and Mary Chain
The Promise Ring
Less Than Jake
Chiodos (original lineup reunion)
Built To Spill
Imagine Dragons
Reverend Horton Heat
Screaming Females
White Mystery
The Henry Clay People
Sister Crayon
The Infected
Environmental Encroachment

+ more TBA