Events such as the killing of unarmed, 18-year-old Michael Brown in Ferguson, Mo., can provide the moral shock that political movements need to build their ranks and bring attention to a community’s afflictions. They can be like the murder of 14-year-old Emmett Till in 1955 or the beating death of Matthew Shepard in 1998 — transformative episodes that remake perceptions and force a society to abandon abhorrent practices.

Or they can be like the 1991 beating of Rodney King by Los Angeles police officers: a horrific moment that failed to create a sustained push for broader, nationwide reforms of policing practices.

For black Americans, the outrage against the police that we’re seeing in Ferguson has appeared in roughly 10-year intervals — from the 1979 beating death of Arthur McDuffie by police, which sparked protest and violence in Miami; to the attack on King, which led to more than 50 deaths and several days of unrest in Los Angeles; to the 2001 shooting death of 19-year-old Timothy Thomas in Cincinnati, which also erupted in protest and rioting and produced a costly economic boycott against the city.

So perhaps America was due for another bout of unrest. But will Ferguson recede in the coming days and weeks, becoming the scene of just another tragic slaying that didn’t lead to meaningful change in police conduct toward black or brown communities? Will history remember Michael Brown less like Emmett Till and more like Rodney King?

I’m optimistic that Ferguson can lead to real change. The church rallies, street demonstrations, marches, looting and targeted violence against police are familiar responses. But there are four key differences in what is unfolding in Ferguson: first, the cumulative effect of recent cases of police misconduct against black people across the nation; second, a backlash against rhetoric that blames poor black youth for the way they are treated by police; third, the use of innovative protest tactics; and finally, the support of allies beyond the black communities that are demanding justice for Brown and reforms in policing.

Ferguson reflects the changing mood in black America, and the realization that police misconduct is not isolated to particular communities but is a nationwide crisis. Since the fatal shooting of Trayvon Martin by self-described neighborhood watchman George Zimmerman on Feb. 26, 2012, a series of killings of unarmed black youths by police and vigilantes has brought black frustration to the boiling point.

Last September, 24-year-old Jonathan Ferrell was gunned down by a white police officer in Charlotte while looking for help after a car crash. The following month, 19-year-old Renisha McBride was shot to death in Dearborn Heights, Mich., by a white man who assumed that the teen was attempting to break into his home and fired at her from behind a locked screen door. She was also seeking help after a car crash.

The outcome of the February 2014 trial of Michael Dunn, a white man who killed 17-year-old Jordan Davis during an argument over loud music in Jacksonville, Fla., angered many black Americans who thought that Dunn should have been convicted for Davis’s death rather than for the attempted murder of the three survivors of the shooting.

And about three weeks before Brown’s killing in Ferguson, 43-year-old Eric Garner died from a police chokehold in Staten Island, N.Y., after telling the arresting officers that he could not breathe.

Police misconduct has often been treated as a local matter. But the cumulative effect of these and other events points to a national challenge, and it is only deepening black mistrust of law enforcement and the criminal justice system.

There is a widespread belief among white Americans, as well as many black ones, that the hairstyles, clothing, music and speech of poor and working-class black youths are the causes of aggressive police reactions — basically, that the kids are asking for it. This belief reflects a long-standing tradition of respectability politics, in which progress against poverty and discrimination must flow from black people behaving differently, better.

In a nationwide 2008 poll by ABC News and Columbia University’s Center on African American Politics and Society, 44 percent of black Americans said they believed that the reason African Americans faced difficulty moving ahead was because they lacked individual initiative. Thirty-seven percent said that the lack of black progress was caused by racism in society.

This divide mirrors the lack of consensus among African Americans about how to deal with racist police practices. Either keep your head down at all times in public to avoid run-ins with police officers — or with white people more generally — or demand that you be treated as equals under the law, just like anyone else, without needing to strive for some flawless ideal.

In the wake of Ferguson, many black and white Americans alike have awakened to the idea that a lack of respectability is not the problem; the problem is policing practices in black and brown communities. In Brown’s case, the allegation of his role in a “strong arm” robbery before his encounter with officer Darren Wilson has not defused protest. Indeed, the accusations heightened residents’ anger, because many fail to see a connection between the alleged robbery and Brown’s shooting, especially since Wilson had no knowledge of Brown’s potential involvement at the time of the shooting. Blame is falling where it belongs — on the officer for his aggressive policing, not on Brown for being less than superhuman.

Missouri Highway Patrol Capt. Ron Johnson, appointed by the governor to oversee security in Ferguson, has eloquently challenged the notion that black youths’ appearance says something about their propensity toward crime. “When this is over,” he told a church audience, “I am going to go in my son’s room. My black son. Who wears his pants sagging. Wears his hat cocked to the side. Got his tattoos on his arm. But that’s my baby.”

Such arguments reflect reality: Embracing respectability does not provide a shield against police misconduct. The stellar credentials of Ferrell, a former Florida A&M University student with a 3.7 GPA who was working his way back to college, did not protect him from being shot down by police. Nor did the professional status of Arizona State University professor Ersula Ore prevent her from being manhandled by a police officer, who wrestled her to the ground after she politely asked why she was being stopped for jaywalking and treated disrespectfully.

Taking the fight online

While the streets of Ferguson have been the scene of protest and confrontation, social media — in particular “Black Twitter” — has emerged as a powerful forum for activism and debate regarding Ferguson, helping sway public opinion by challenging racially biased interpretations of Brown’s killing. For example, black people on Twitter and Facebook have posted images of themselves in formal clothes alongside pictures of themselves in informal attire, asking whether they deserved to be under suspicion because of the way they were dressed. They have posted individual and group photos with their hands raised in a gesture of surrender — as witnesses reported Brown did when he was shot — with hashtags such as #HandsUpDontShoot and #blacklivesmatter. And they have used social media to coordinate vigils for Brown and other victims of police brutality, to organize rallies across the country, and to post links to live-streaming sites that show the Ferguson protests in real time.

With Ferguson more than ever before, social media has become the game-changer of black activism, filling the void left by the weakening of traditional civil rights leaders and organizations that used to play a vital role in interpreting events for the black community, but now have less credibility in that community than they did a generation ago.

Increased anger and distrust, shifting perceptions of blame, and new protest techniques will go only so far. If Brown’s death is to lead to a true movement, it must transcend the street unrest and hashtag angst that too often stand in for political organizing.

To succeed, movements require strong organization and coordination. The kinetic energy from protests in Atlanta, Los Angeles, New York, Philadelphia, Baltimore, the District and elsewhere needs to be harnessed to build local organizations aimed at combating police brutality. Local activism, in turn, should be linked to regional and national efforts and protest campaigns such as the Dream Defenders in Florida and the Moral Mondays movement in North Carolina and Georgia . This is how numbers and influence grow.

A movement will also need allies beyond black communities, such as immigration reformers and LGBT groups, whose constituencies are also affected by police brutality. And in the best tradition of the civil rights movement, allies should be sought abroad. Highlighting human rights abuses in the United States on the world stage — as Paul Robeson, W.E.B. Du Bois, Malcolm X and Martin Luther King Jr. did during the Cold War — will put more pressure on America to live up to its professed ideals of freedom and equality.

Lastly, movements require patience and persistence. Once the marching stops and the cameras leave Ferguson, the grinding work of organizing will have to take hold. The 1955-1956 Montgomery bus boycott lasted a year until victory was declared, and congressional legislation banning racial discrimination in public accommodations and voting did not pass until a decade later. It took 17 years for LGBT activists to repeal “don’t ask, don’t tell.” Change does not come overnight.

What may keep Ferguson from becoming a national transformative event is if “justice” is narrowly confined to seeking relief for Brown and his family. If the focus is solely on the need for formal charges against Wilson, a fair trial, a conviction, a wrongful-death lawsuit — rather than seeing those things as part of a broader movement that tackles stand-your-ground laws, the militarization of local police, a requirement that cameras be worn by police on duty and the need for a comprehensive federal racial-profiling law. If justice remains solely personal, rather than universal.

Some believed that the beating of Rodney King and the riots that followed would lead to improved policing in black communities. But energy went toward rebuilding, not reforming. Ferguson presents an opportunity to pursue a different course. Let’s turn this tragedy into a tipping point.

Fredrick Harris is a professor of political science and the director of the Center on African American Politics and Society at Columbia University. He is the author of “The Price of the Ticket: Barack Obama and the Rise and Decline of Black Politics.”