Robin Thicke is among several popular acts set to headline the 2013 Virgin Mobile Freefest this September.

The concert, which takes place on the 21st at Merriweather Post Pavilion in Columbia, Maryland, is free to enter but organizers accept donations on behalf of the Southeast Washington homeless youth shelter, which was built from proceeds garnered from previous concerts. Those music lovers who want to pay for their tickets to give to the shelter are encouraged to do so with a little early ticket release date of August 8. The rest of the tickets will go on sale the next day, but get them fast; last year all 50,000 tickets sold in just minutes.

The full lineup:

Vampire Weekend
Robin Thicke
The Avett Brothers
Pretty Lights
MGMT
Kaskade
City and Colour
Icona Pop
CHVRCHES
The Knocks
Black Joe Lewis
Sky Ferreira
Little Green Cars
Madeon
Gareth Emery
Washed Out
Manufactured Superstars Congorock
TJR
Ghost Beach