No specific dates, stages, or times have been given, but there are some interesting and impressive surprises. Among the grounds stage headliners announced via USA Today:

New Order
Rise Against
Kip Moore
Ray LaMontagne
Joan Jett & The Blackhearts
Nas
Brand New
The Neighbourhood
Fitz & The Tantrums
Ludacris
Five Finger Death Punch
The Fray
The Head And the Heart
Neon Trees
The Airborne Toxic Event
Tegan And Sara
B.O.B.
Robert DeLong
Melissa Etheridge
Bonnie Raitt
Atmosphere
Girl Talk
REO Speedwagon
Ben Harper and Charlie Musselwhite
ZZ Ward
Umphrey’s McGee
Cheap Trick
Walk Off The Earth
Ziggy Marley
Kongos
A Great Big World
.38 Special
Jake Miller
Kool And The Gang
Switchfoot
Jake Bugg
Yonder Mountain String Band
Bleachers
O.A.R.
Timeflies
Wailers
Los Lonely Boys
Scotty McCreery
Pentatonix
SoMo
Blackberry Smoke
Rusted Root
George Thorogood & The Destroyers
DJ Pauly D
Kansas
Nitty Gritty Dirt Band
Trombone Shorty & Orleans Avenue
Michael McDonald
Clay Walker
The Crystal Method
Dennis DeYoung and the music of Styx
Matisyahu
Crowder
Best Coast
Taj Mahal Trio
David Nail
The Hold Steady
Delta Rae
Cowboy Mouth
Saints Of Valory
Bombino
Kopecky Family Band
Moon Taxi
St. Lucia
Wild Feathers
James Hunter Six
San Fermin Bad
Suns
Kitten
Wild Cub
Foy Vance