MoveOn.org is a prominent progressive public policy advocacy group and political action committee founded in 1998 by Wes Boyd and Joan Blades, a California couple known for creating the flying toaster screen saver. It originated as an online petition titled 'Censure President Clinton and Move On to Pressing Issues Facing the Nation,' which urged Congress to forgo the impeachment of President Bill Clinton and focus on more urgent matters. This petition went massively viral, marking one of the earliest examples of internet-driven activism, and propelled MoveOn into a major force in progressive politics. The organization rapidly expanded, becoming one of the largest grassroots campaigning communities in the United States with millions of members. MoveOn gained national prominence for its opposition to the Iraq War, producing influential ads criticizing President George W. Bush's policies, and has since mobilized on a wide array of issues including social justice, environmental protection, healthcare reform, and electoral politics.

MoveOn operates through two main entities: MoveOn Civic Action, a 501(c)(4) nonprofit focused on advocacy and issue-based campaigns, and MoveOn Political Action, a political action committee dedicated to electoral work such as candidate endorsements and voter mobilization. In 2011, it launched SignOn.org as a platform for hosting internet petitions, which evolved into MoveOn Petitions by 2013. The group did not endorse a candidate in the 2020 Democratic presidential primary but actively supported Joe Biden in the general election. For the 2024 cycle, MoveOn endorsed Vice President Kamala Harris as the Democratic nominee. Rahna Epting has served as Executive Director of both MoveOn Civic Action and MoveOn Political Action since 2019. Over more than two decades, MoveOn has emphasized collective people power to build a more equitable society, though it faced internal transitions, including the inactivity of some initiatives by 2005 and closures by 2008.

While celebrated for its innovative use of digital tools in activism, MoveOn has drawn criticism for its partisan approach and influence in Democratic politics, including allegations of astroturfing in some campaigns. Nonetheless, it remains a key player in progressive networks, with a focus on rapid response organizing and member-driven petitions.