Social movements are the matrix of many forms and formats (technologies, genres) of media that contest dominant power. Such media are in many ways the lifeblood of such movements. Media activism denotes collective communication practices that challenge the status quo, including established media. Frequently, such media are underfunded or unfunded and have a much shorter life cycle than capitalist, state, or religiously funded media. They are a “tribe” within a much larger continent of nanomedia (also called alternative media and citizens’ media). Their functions may spill over at times within the operation of established media, especially in times of social turbulence and crisis. The “dominant power” in question may be quite variously perceived. Extreme-right populist movements, as in several European countries, may define the political establishment as having betrayed the supposed racial purity of the nation, or in the case of India’s Islamophobic Hindutva movement, as having traduced the nation’s religious purity. Labor movements may attack capital, feminist movements, or patriarchal and sexist structures. Sometimes these movements may be local, or regional; other times, they are transnational. The impact of these media is still a matter of considerable debate. Often, the debate begins from a false premise—namely, the frequently small size and/or duration of many social movement media projects. Yet women’s right to vote and the abolition of slavery in the Americas were not won overnight, and neither was the dismantling of South Africa’s racist apartheid system. The Hindutva movement goes back over a century. We should not hold social movement media to a higher standard of impact, any more than we should ascribe instantaneous power to established media. Social movements wax and wane, and so do their media projects. But the persistence of some such media activism between the peaks of movement activism is generally essential to the regeneration of social movements.