Over the past few years we've grown used to the iconography of protest. In the wake of the Arab Spring, images of angry young street demonstrators shouting slogans, wielding signs, and confronting security forces have become almost commonplace. But just as often we've seen campaigns of public protest flounder or go into reverse: just look at Egypt and Libya, to name the most prominent cases. The recent surge of street demonstrations in Sudan once again confronts us with a fundamental question: How does public protest undermine authoritarian governments? Are demonstrations really the key to toppling autocrats? Research shows, in fact, that demonstrations are just one of many tools that civil resistance movements can use to effect change. Successful movements are those that use a wide array of methods to pressure their state opponents while keeping their activists safe. The demonstration tactic we're used to seeing is just one of many hundreds of tactics available to civilians seeking change -- and successful campaigns for change must use more than just a single tactic. Maria Stephan and I conducted research on a related but broader question: "When does civil resistance work?" The results of our research show that opposition campaigns are successful when they manage to do three key things: (1) attract widespread and diverse participation; (2) develop a strategy that allows them to maneuver around repression; and (3) provoke defections, loyalty shifts, or disobedience among regime elites and/or security forces. Attracting participation is perhaps the most important of these tasks, since the ability to provoke defections and outmaneuver opponents often depends on whether the movement enjoys large and broad-based support. The most important singular factor for a successful campaign is its participation rate. According to the NAVCO data set, which identifies the outcomes of over 300 nonviolent and violent campaigns worldwide from 1900-2006, none of the cases failed after achieving the active and sustained participation of just 3.5 percent of the population -- and some of them succeeded with far less than that. Of course, 3.5 percent is nothing to sneeze at. In the United States today, this constitutes over 11 million people. But how do movements get this large in the first place, especially in countries where overt participation in a mass movement is highly risky? One way organizers can grow their movement is by including tactics that are safer and therefore more attractive to risk-averse participants. For example, instead of relying solely on demonstrations or protests, many movements will allow people to participate through "electricity strikes" where people shut off their electricity at a coordinated time of day, or by banging on pots and pans in the middle of the night to signal the power in numbers. Engaging in these types of actions may draw in more ambivalent people while also allowing them the opportunity to develop a sense of identity with the movement and its goals. In Chile under Pinochet, for example, outright demonstrations against the dictator were far too dangerous. In one instance, Pinochet was so threatened by the subtext of some popular songs that he banned public singing; it didn't take much. But when people began to bang on pots and pans, it let them demonstrate their defiance anonymously in the safety of their own homes. As the people's metallic clamor for change became louder and louder, anti-Pinochet organizers and their supporters became emboldened to press for more disruptive and overt action. A similar movement is underway in Egypt today, where the "Masmou" movement has led thousands of people to bang on pots and pans inside their homes at 9 p.m. each night to signal that there are viable alternatives to both the al-Sisi government and the Muslim Brotherhood. In highly repressive environments there is, indeed, safety in numbers. And actions like this can signal that one is not alone, while making it quite difficult for the government to crack down on participants. Once people do begin to mobilize, the effects on the internal politics of a tyrannical regime can be intense. As Gene Sharp rightly argued, no regime is monolithic. Every leader is 100 percent dependent on the cooperation, obedience, and help of the people that form the regime's pillars of support: security forces, the state media, business or educational elites, religious authorities, and civilian bureaucrats. And when such people begin to reevaluate the regime's role in their long-term interests, they can actually be pulled away from supporting the leader. This is much more likely to happen the more people are mobilized against the opponent. Because no regime loyalists in any country live entirely isolated from the population itself. They have friends, they have family, and they have existing relationships that will bring with them in the long term, regardless of whether the leader stays or goes. As the literary critic Robert Inchausti is credited as saying, "Nonviolence is a wager -- not so much on the goodness of humanity as on its infinite complexity." Take an example from the so-called "Bulldozer Revolution," a Serbian people power revolution against Slobodan Milosevic that toppled him in October 2000. In this case, once it became clear that hundreds of thousands of Serbs were descending on Belgrade to demand that Milosevic leave office, policemen ignored the order to shoot on demonstrators. When asked why he did so, one of them said: "I knew my kids were in the crowd." This policeman wasn't alone in Serbia or elsewhere. We find that, in general, security forces tend to defect much more often when they face nonviolent campaigns (as compared to armed uprisings), particularly as the numbers rise. Controlling for other factors, security forces are about 60 percent likely to defect when confronted with the largest nonviolent campaigns and over 30 percent likely with the average-sized nonviolent campaign. The defection of security forces occurred within the ranks of the Iranian armed forces during the anti-Shah resistance, within Filipino armed forces during the anti-Marcos uprising, and within the Israeli military during the first Palestinian Intifada, to name but a few examples. And these loyalty shifts can be crucial for the outcomes of these campaigns: They increase their chances of success by over 60 percent. Of course, demonstrations -- and people power movements in general -- tend to fail as often as they succeed. But when we look at outright failures -- such as Tiananmen Square, the 1956 Hungarian uprising, or the 2007 Saffron Revolution in Burma -- a few patterns become evident. The failed campaigns never spread to include vast proportions of the population, and failed to shift between highly risky tactics and safer ones. But they also failed to establish a long-term strategy to make the campaigns sustainable, which was especially important given the brutality of state repression. The average duration of a nonviolent campaign was between two-and-a-half and three years, but few of these campaigns had a long-term strategy, besides the wishful hope that tactical victories might make the regime comply with their demands. Campaigns of civil resistance are underway in many countries around the world, from Bahrain to Maldives, from Turkey to Bulgaria. In all of these cases, movement planners must carefully analyze the political effects that tactics like demonstrations have. If these tactics fail to increase sympathy for the campaign at home or abroad, diversify the base of participants, and encourage defections among regime elites, then they are not helping the movement's chances of succeeding. But rather than abandoning the struggle because demonstrations stop working, movement leaders would do well to appreciate the many other nonviolent methods of protest and noncooperation they can bring to bear against their opponents. The campaigns that ultimately succeed will be the ones that fully embrace Sun Tzu's warning that "tactics without strategy is the noise before defeat."