On October 15 last year, 200,000 people marched in Madrid. They were part of a Spanish movement that has come to be known as 15-M—after May 15, the date of its first action—or the indignados. The movement has broad support from the Spanish public, both right and left, with 73 percent approving in recent polls. Participants and organizers consistently report that “regular people” and “first time” protestors, “not just movement activists,” are deeply involved in the assemblies. As Irache, a public school teacher participating in the march, told us, “The crowd that day came from all walks of life in the city.”

The six-hour march past the city’s financial and tourist center to the iconic Puerta del Sol was animated by the now-familiar indignado chants: “if we can’t dream, you won’t sleep”; “they don’t represent us”; and “these are our weapons,” as protesters lifted their hands in the air, a sign of agreement at assemblies.

Along the route there were more strollers than police. But at least for North American eyes, what was most striking was the absence of banners. True to the principles of 15-M, almost no one came with signs representing parties, unions, or any other organized groups. The only exceptions were the green T-shirts of the “Green Tide,” an ad hoc movement of teachers and students to defend public education against drastic cutbacks. This group, Irache assured us, was there to support the protest, and not part of 15-M itself.

The lack of banners is essential to the work of the indignados. As a movement, 15-M does something novel, bringing people together as equal citizens, not as representatives of particular interests or bearers of particular identities. Claiming broad allegiance—8 million people say they have participated in at least one 15-M event—the movement has broken the barrier between political activists and ordinary citizens. It shares principles of nonviolence and nonpartisanship with the Occupy movement and other peaceful demonstrations around the world. But its central demand—for a direct, deliberative democracy in which citizens debate issues and seek solutions in the absence of representatives—is unique. 15-M represents a striking challenge to traditional political actors—parties, civic associations, unions—and to democratic politics itself.

15-M has evolved to become a new political subject, distinct from the original Internet-based group—Democracia Real Ya, or Real Democracy Now (DRY)—that organized the mobilization of May 15, when about 20,000 people gathered in Puerta del Sol. Three months earlier, on a Sunday night in February, ten people met in a Madrid bar to began planning the event. They had already been exchanging opinions online about the political and economic situation in Spain. Their meeting ended with both a slogan—“Real Democracy Now: we are not goods in the hands of politicians and bankers”—and plans to hold a demonstration the week before the municipal elections of May 22.

Although DRY targeted unemployment and mortgage reforms, the main message was not about the economic crisis but about the breakdown of political accountability and representation. Some commentators on the left criticized this message as insufficiently radical, but more than 500 organizations and movements supported the May 15 event, even though DRY rejected official collaboration with any political party, union, or other expression of institutionalized political ideology.

The gathering was a success. The widespread disaffection of Spanish citizens took center stage at one of the nation’s most visible sites.

That was supposed to be it.

But not all of the participants left the plaza. Initially about 50 decided to stay. By midnight, this group had dwindled to just over twenty. They decided to spend the night in the square. Most of the holdouts did not belong to any social movement; they were not seasoned activists or even members of DRY. They stayed, some of them said, because they were “tired of demonstrations that finish happily and then: nothing.”

A physics PhD student acted as moderator for the group discussions, and a 28-year-old journalist spoke on behalf of the group when the police asked them to leave. They managed to stay in the square until the next morning and, in exchange, guaranteed the police that they were not going to riot or disturb the peace. They organized into small committees to look for food and makeshift mattresses. One of the protesters used a smart phone to spread word of the occupation, with the Twitter hashtag #acampadasol.

The next morning, Monday, the police chased them out, but messages on Twitter and Facebook called for another sleepover that night. This time nearly 200 people attended. The police forcefully removed the occupiers before midnight. By Wednesday nearly a thousand people were camped out. A judicial injunction against the encampment only emboldened the growing movement. On Thursday the numbers increased further, and the first tents appeared. Protesters in Barcelona and Seville followed suit, setting up camp in public spaces. By Friday, May 20, more than 10,000 people were camped in the Puerta del Sol. And many more came on Saturday to express solidarity. Twenty thousand people spent the day holding back the police.

The central organizing principle of 15-M is individual participation. The movement is infused with a participatory ethos: everyone is expected to take part in all aspects of the group. Strikingly, the movement rejects the principle of representation. Some participants belong to other groups or organizations, but within the movement, individuals do not speak for collectives; they speak in their own voices, for themselves, relying on their own judgments.

This is highly unusual in Spain, which is filled with progressive networks and organizations focusing on diverse interests: housing, the environment, the working class, anarchism, feminism, and many others. Until now, the work of advancing social justice has consisted in suturing together often-fragile coalitions, assuring the right mix of representation at events, and facing the usual controversies that arise when an array of interest groups try to work together.

15-M challenges traditional political actors and democratic politics itself.

15-M has broken with that coalition-politics logic. Assemblies only accept proposals by consensus, and proposals are developed by ad hoc working groups, not permanent institutions committed to single issues. There is no interest group representation and no bargaining. The decisions that touch all must be accepted by all. And the process is evolving: one very active working group is tasked with improving the decision-making procedure.

Participants in the encampment understand that they are pursuing a new form of politics, a re-conquest of public space for equal citizens, and a radical questioning of the political status quo. This is apparent not only in the way the assemblies make decisions, but in how they talk generally. Every assembly starts with a statement of expectations for participants: be respectful, give only short speeches, keep an open mind, and embrace pluralism. All newcomers are welcome and all meeting minutes are public. Everyone is entitled to speak at every assembly, and all are bound by the same rules. There are strict codes to ensure civility. Shouting, insulting, and speaking of “enemies” are forbidden. If someone speaks loudly, the moderator will remind her that she has to be fair and she has to respect others’ proposals and ideas. The assemblies always start with an agenda and end on time.

Like the decision-making process, the assemblies are works in progress. Assemblies frequently consider how to avoid the pitfalls of deliberation—sometimes criticized for giving too much power to the educated and articulate—and of consensus—sometimes criticized for privileging the status quo.

These practices pair nicely with theories of direct and deliberative democracy. But the movement as a whole does not explicitly draw on political theory as much as, in the words of one activist, “conversation in social networks and lots of common sense.” The argument for consensus decision-making is that it opposes the way professional politicians debate and talk, which is seen as instrumental and in the service of narrow interests.

The dedication to individual participation and the refusal of representation were tested almost immediately. Just after the first demonstration, unions, neighborhood associations, social movements, and other organizations joined the camp hoping to express their goals at Puerta del Sol’s nightly assemblies. But the campers—acampados—consistently rejected these proposals. 15-M addresses “society as a whole,” one of the campers told us in an interview. It “has nothing to do with the defense of a certain interest, or with the image of one or another sector.”

During the first week, a banner with feminist slogans was taken down. The decision was intensely controversial, and still echoes on the Internet. But the reasons for the removal had nothing to do with the cause of feminism. All banners were taken down—banners of trade unions, anarchists, communists, and social movements, including DRY itself. Any slogan that branded the assemblies with a group identity was disavowed as a distraction from the movement’s political strategy and self-understanding: equal citizens in discussion about the common good. 15-M has even challenged DRY. In many cities, conflict has emerged between the acampados and members of DRY, whom many acampados see as elitist.

Because of its political innovations, 15-M has been received with ambivalence by urban social movements in Madrid and elsewhere in Spain. Its rejection of banners and its extremely civil mode—both viewed as reformist rather than revolutionary—have aroused particular suspicion. But the movement’s popularity has deflected open criticism. Other activists recognize that the high degree of mobilization offers an opportunity. An activist from a social and arts center in Madrid told us, “If we leave the ghetto, 15-M can help us express our goals and learn a new way to expand.”

The occupation of Puerta del Sol ended in July, but the movement has spread to the city’s outer boroughs and across Spain. Anyone can join its working groups via its Web site. The working groups represent a kind of direct democracy, where people come together as individuals to work on policy solutions to the country’s problems. Topics range from proper democratic procedures to financial transparency and mortgage reform. The working group on financial transparency, for example, has uncovered what appears to be evidence of price-fixing on inter-bank lending rates, and the working group on housing and mortgages has been able to stop some evictions. Meanwhile, a working group on assemblies is creating a dispersed deliberative network that will allow people to debate policy from anywhere.

15-M has shifted the tenor of political debate in Spain, placing disaffection with representative democracy at the center of discussion. And this disaffection extends to all major political actors. Although the movement’s policy concerns are closer to preoccupations of the left, its model of directly deliberative democracy challenges the institutional limits of leftist parties and much of their theoretical imagination.

As with the Occupy movement in the United States, it is hard to know how far 15-M can go in creating change. Spain’s recent national elections delivered an overwhelming victory for the rightist Popular Party. Coupled with the results of the most recent provincial and local elections, this victory has put Spain under near-total right-wing dominance for the first time since its transition to democracy. But 15-M remains energetic. Its insistence on deliberation, civility, and internal democracy has encouraged erstwhile non-activists to join and play important roles. While 15-M’s proposals may deviate from traditional leftist conceptions of social transformation, the movement’s rejection of partisanship has empowered the left at a time when social democratic parties throughout Europe are fighting for their lives.

Occupy bears some similarities to 15-M, especially in the criticisms directed against it: that the movement needs more concrete proposals, institutional allies, and tangible targets. And like 15-M, Occupy keeps its distance from political parties, although that charge is perhaps less controversial in the United States, which lacks leftist parties that can win elections.

But there are also large differences. The language of group identity—race, gender, ethnicity—is central to social justice in the United States, and Occupy does not reject group claims. Indeed, by attempting to speak universally, Occupy has at times drawn charges that it may be silencing minority voices. Groups such as Occupy the Hood have made the struggles of people of color their primary focus. Furthermore, because economic inequality has been so central to Occupy’s political imagination, unions and union organizers have been more visible than have their counterparts in Spain, and both sides have shown greater receptivity to dialogue, though not without ambivalence.

In spite of the strict ban on special-interest promotion, the indignados are not suggesting that unions or other groups have no place in a radically democratic movement. Rather, to play a part, they cannot allow their demands for just democracy to be mere slogans or election strategies. Interest groups need to focus more on speaking for the common good, as some union leaders have acknowledged in efforts to connect with Occupy. And they need to understand that ossified leadership structures and dependence on political parties are at odds with the larger goal of achieving a genuinely democratic renewal.