Previously, Penniman was executive director of the Huffington Post Investigative Fund, which he founded with Arianna Huffington in 2009. Supported by large foundations and The Huffington Post, the operation established a multi-media newsroom of journalists. It was profiled in media publications, including the American Journalism Review and the Columbia Journalism Review. In 2011, it merged with the Center for Public Integrity.
Penniman founded the American News Project, an early experiment into online video journalism and served as the Washington director of the Schumann Center for Media and Democracy, where he worked closely with broadcaster Bill Moyers. Moyers and Penniman first met in 1999, when Penniman was running a national grassroots organization called the Alliance for Democracy, which focused primarily on campaign finance reform and the effects of economic globalization.
From 2005-2006, Penniman was the publisher of The Washington Monthly magazine. Before that he was the executive editor of a progressive news and opinion website called TomPaine.com perhaps best known for the "op ads" it regularly ran on the opinion page of the New York Times.
In 2016, Penniman and co-author Wendell Potter published Nation on the Take: How Big Money Corrupts Our Democracy And What We Can Do About It. Nation On The Take details the history of money in politics and exposes the effects of the influence industry and political money on policy making and everyday Americans. The book was praised by the likes of historian Doris Kearns Goodwin, who stated "There could be no more important or timely book"; New York Times columnist Nicholas Kristof, who referred to it in one of his pieces as an "eye-opening new book about money in politics"; former Republican Senator Alan Simpson; Democratic Senator Bernie Sanders; among many others.
Penniman has served on multiple nonprofit boards and advisory boards, including the Homeless Empowerment Project, which publishes Spare Change News, the Center for Responsive Politics and the Roosevelt Institution. He serves on the Advisory Council of Represent.Us, a nonpartisan anti-corruption organization.
He graduated from St. Lawrence University in 1992 with a degree in philosophy. While there, he served on the student senate, was an adviser to the board of trustees, and started multiple student groups.
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- Board of Directors, Everglades Foundation
- Pulitzer Report Contains Lots of Clues, St Louis Journalism Review, May 1999, by Charles L Klotzer