In 1999, Greene traveled to Botswana and South Africa on behalf of the United States Information Agency to encourage young voters to participate in the upcoming elections.

Greene is a former National Director of Project Vote, the 501c3 voter registration arm of Association of Community Organizations for Reform Now (ACORN).

[7] Greene co-founded Define American in June 2011 with Jose Antonio Vargas, Jake Brewer, and Alicia Menendez.

She was a member of the Citizen's Debate Commission and previously served on the board of directors of the American Prospect Magazine; Demos; Youth Vote Coalition; The Entrepreneurial Development Institute (TEDI).

On the edition of May 4, 2012 of America Live, Greene referred to fellow debater Tucker Carlson as a "bow-tying white boy", in a discussion about Massachusetts Senate candidate Elizabeth Warren's decision to list herself as a member of a racial minority in the Association of American Law Schools desk book, a directory of law professors, in the 1980s and 1990s, because her great-great-great-grandmother was listed as Cherokee.

[9] Host Megyn Kelly later apologized to Carlson and her audience for the remark on behalf of the program, calling it "an inappropriate name" that was "not consistent with our standards".