Stevie Wonder, Kings of Leon, Alicia Keys and John Mayer have volunteered their time to attend the second Global Citizen Festival in New York’s Central Park, and organizers hope you will, too.

Tickets are again free for the Sept. 28 event, but must be earned through acts meant to help end extreme poverty around the world. The festival is designed to coincide with the UN General Assembly meeting and put pressure on world leaders to address the needs of the world’s poor. Fans can earn points toward tickets through simple tasks like sending letters to political leaders or reposting information through social media.