Rainey is the activism director of EFF, which defends liberty in the digital world. She is also a founder and steering committee member for the Bradley Manning Support Network, a network of individuals and organizations advocating for the release of accused WikiLeaks whistleblower Pfc. Bradley Manning. Additionally, she serves on the board of the directors for the Bill of Rights Defense Committee, a nonprofit whose mission is to organize and support an effective, national grassroots movement to restore civil liberties guaranteed by the Bill of Rights. She is also a steering committee member of the Internet Defense League, a netroots coalition working to fend off threats to the free and open Web.
Recently, she co-founded Freedom of the Press Foundation, a nonprofit organization that crowd-sources funding to supporting unique, independent, nonprofit journalistic institutions, where she also serves as Chief Operating Officer.