The child of political activists, Mattie has been doing direct action, community organizing and campaign work her entire life (including as an 11 year-old doorknocker on Paul Wellstone's first Senate campaign). A 2001 graduate of Swarthmore College, she studied political science and organized students and staff around issues of global economic justice, local race politics, and a campus-based living wage campaign.  After graduation Mattie was a writer and researcher for the Applied Research Center, a racial justice "think and do tank."

In 2004 she wrote two chapters of the book, How to Get Stupid White Men Out of Office, which she toured around the country, organizing and speaking on behalf of the League of Pissed Off Voters.  In despair over that election, Mattie moved to Salvador, Brazil, where she met her husband, taught salsa dancing and later worked for a study abroad program.  Since returning to the United States, Mattie has worked for Wellstone Action--first as the director of Campus Camp Wellstone, and now as the Training Director as well volunteered with a number of local campaigns. She is the proud mom of a beautiful baby boy named Luca.