How to Make Big Things Happen


By Damon Centola

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How to create the change you want to see in the world using the paradigm-busting ideas in this "utterly fascinating" (Adam Grant) big-idea book.​

Most of what we know about how ideas spread comes from bestselling authors who give us a compelling picture of a world, in which "influencers" are king, "sticky" ideas "go viral," and good behavior is "nudged" forward. The problem is that the world they describe is a world where information spreads, but beliefs and behaviors stay the same.
When it comes to lasting change in what we think or the way we live, the dynamics are different: beliefs and behaviors are not transmitted from person to person in the simple way that a virus is. The real story of social change is more complex. When we are exposed to a new idea, our social networks guide our responses in striking and surprising ways.
Drawing on deep-yet-accessible research and fascinating examples from the spread of coronavirus to the success of the Black Lives Matter movement, the failure of Google+, and the rise of political polarization, Change presents groundbreaking and paradigm-shifting new science for understanding what drives change, and how we can change the world around us.



The science of networks is the study of how things spread. How do the connections we share with the people around us affect the way that diseases, ideas, trends, and behaviors move through communities and societies and around the world?

In the spring of 2020, as I was finishing work on this book, the world was suddenly transformed by two powerful new examples of things that spread very far, very fast. The first, of course, was the novel coronavirus, which emerged in a market in Wuhan, China, and, in a matter of weeks, spread throughout China, then to the Middle East and Europe, and from there to every corner of the world.

What made the virus so deadly and disruptive was how easily it could be transmitted. It was small, it was hard to kill, and it was airborne. You could catch it from someone standing a few feet away from you, and it lingered in the air for hours. What made the virus even more insidious was the fact that if you caught it, you could then spread it to others before you felt any symptoms, before you even knew you’d been infected. Every person was a potential source of contagion. Every contact was a mode of transmission. A hug. A handshake. Receiving a package in the mail. Accepting a piece of paper from your colleague. And so the disease spread rapidly, at choir practices and funerals and family reunions, through hospitals and nursing homes and meatpacking plants, between husbands and wives and between complete strangers. By June, more than six million people had been infected worldwide, a third of them in the United States. Once the virus took hold, it expanded exponentially.

But something else was spreading that spring. It wasn’t a disease. It was a behavior.

Governments around the world reacted differently to the coronavirus pandemic—some responded much more quickly than others—but within a few months, public health advice worldwide had coalesced around four basic preventive measures: Wash your hands. Stay at home. Wear a mask. And stay at least six feet away from other people. As these directives took shape, a new question emerged: Would people follow them? Could the entire world change its behavior in such dramatic ways?

People looked first to their friends and neighbors. Were they wearing masks? Were they social distancing? Mostly, remarkably, they were. In many communities—small towns and large cities—the sidewalks were nearly empty. People stayed home. If they did go out, they usually wore face masks. And they afforded one another exaggeratedly wide berths as they passed on the street. In country after country, people changed the way they worked, socialized, went to school, raised children, and went on dates. New behavioral norms had sprung up, seemingly overnight, and they had propagated across the globe.

Gradually, these behaviors changed the course of the disease. After weeks of headlines full of death and despair, there was good news for the first time in months: the spread of the disease was slowing. New cases were going down. Hospital intensive-care units were emptying out.

And then the weather warmed. People began to weary of the daily reminders to maintain their white-knuckled vigilance. Summer was arriving. And the new norms began to unravel.

Some people stopped wearing masks, others became less cautious about social distancing. Their friends and neighbors tried to figure out what to do. Which behaviors were acceptable? Which were overly cautious? Which were selfish or reckless? Different communities responded differently. Some groups wore face masks; others didn’t. Some gathered together; still others kept their distance.

The disease, meanwhile, kept spreading the same way as before. Every person, every surface, every contact remained a potential source of infection. And the caseload continued to rise.

For nearly a century, scientists have believed that behaviors spread just like viruses do. But as the world saw in 2020, the spread of human behavior in fact follows very different rules than the spread of diseases.

Today, epidemiologists and public health experts can forecast the path of a virus, and they can use that science to develop policies to help slow it down. But how can we forecast the spread of new behaviors? How can we identify policies that will improve the uptake of positive behaviors? How can we recognize policies that will unintentionally cause those behaviors to unravel? Why do the rules of social influence seem to vary with culture and identity, and how can we ever hope to understand these complexities?

This book is an attempt to answer those questions. In the pages ahead, I’ll show you what the brand-new science of networks tells us about how and why and when human behavior changes. I’ll show you the factors that determine the spread of social change, explain why we’ve misunderstood them for so long, and reveal how they really work.

Behavior change, we now understand, is not like a virus, spreading through casual contact. It does follow rules, but learning these rules takes us beyond the spread of diseases to reveal a process that is deeper, more mysterious—and much more interesting.


In 1929, Werner Forssman was a twenty-five-year-old heart surgeon with a big idea. He had invented a radical new lifesaving procedure that he thought would change the world. But the medical community met his idea with contempt: he was ridiculed by his colleagues, fired from his job, and driven from the field of cardiology. Thirty years later, Forssman was working as a urologist in a small town in the remote hills of Germany. One night at the local pub, he received a phone call with some startling news: his long-ago discovery had won the 1957 Nobel Prize in Medicine and Physiology. Today, cardiac catheterization is used in every major hospital around the world. How did Forssman’s unpopular innovation become one of the most widely accepted procedures in medical science?

In 1986, American citizens could be incarcerated for up to five years for possessing marijuana—a jail sentence that would forever alter a person’s prospects for financial success, marriage, and even political participation. Today, storefronts in shopping malls sell marijuana openly and pay federal taxes on the proceeds. How did a behavior that was both illegal and regarded as socially deviant become so acceptable that previously stigmatized “drug dealers” became part of the mainstream American business community?

In 2011, internet powerhouse Google launched its new social-media tool, Google+. Although Google had over a billion users worldwide, the company struggled to transfer its dominance in the search-engine market to the social-media market. By 2019, Google+ was forced to shut its doors. During the same period, the start-up Instagram entered the arena. It reached one million users within two months. Within eighteen months the company was purchased by Facebook for $1 billion, and by 2019 Instagram had become a staple among social-media users. What did Google do wrong? And how did Instagram, with fewer resources and less time, outcompete the search-engine juggernaut?

In April 2012, the hashtag #BlackLivesMatter was first posted on social media in response to a jury’s acquittal of the man who shot and killed seventeen-year-old Trayvon Martin. In the two years that followed, several police-related deaths of African American men and women were reported in the news and on social media, but by June of 2014 #BlackLivesMatter had been used only 600 times. Two months later, however, the death of eighteen-year-old Michael Brown in Ferguson, Missouri, triggered a revolution: within months, #BlackLivesMatter had been used more than a million times, and a national movement to protest police violence was underway. Six years after that, in response to the killing of George Floyd in May 2020, #BlackLivesMatter transformed again, this time into a global phenomenon, with solidarity protests in more than 200 cities worldwide and new federal legislation to reduce police violence. What happened to transform decades of overlooked police violence into a powerful, self-organized popular movement?

This book is about change. How it works, and why it so often fails. It’s about the spread of unlikely innovations, the success of fringe movements, the acceptance of unpopular ideas, and the triumph of contentious new beliefs. And it’s about the strategies that help them succeed. Those success stories all have one thing in common: the radical new ideas at their core all expanded and spread through social networks.

I have a unique perspective on these questions because I am a sociologist who studies the science of social networks. In fact, over the last couple of decades, my ideas have helped shape this new field. In the fall of 2002, I made a series of discoveries that altered our scientific understanding of social networks, and launched a new way of studying how change spreads. The resulting insights have helped to explain why social change can be hard to predict, and why it so often confounds our most trusted ideas about which strategies will work and which others will fail.

For decades, our standard ideas about social change have been based on a popular metaphor—that change spreads like a virus. Recently, we have all been reminded how a virus works: one person gets infected, they pass it on to one or two or three (or a hundred) others, and the contagion spreads through the population. The idea that “influencers” are the key to spreading innovations is based on the notion that well-connected individuals can play an outsize role in the spread of a disease—for instance in a viral pandemic. Similarly, the idea that stickiness is essential for a successful social-marketing campaign is based on the idea that certain viruses are particularly infectious.

These viral metaphors are useful when we’re talking about the dispersal of simple ideas or information (headline news of a volcanic eruption, for example, or the marriage of royal celebrities). And those bits of information really are contagious: easy to catch, easy to transmit. But there’s a big problem with the viral metaphor: to create real change, you need to do more than spread information; you must change people’s beliefs and behaviors. And those are much harder to influence. Viral metaphors are able to describe a world where information spreads quickly yet beliefs and behaviors stay the same. It is a world of simple contagions—catchy ideas and memes that spread quickly to everyone but lack any lasting impact on what we think or how we live.

But social change is far more complicated. Innovative ideas and behaviors do not spread virally; simple exposure is not enough to “infect” you. When you are exposed to a new behavior or idea, you don’t automatically adopt it. Instead, you have to make a decision about whether to accept or reject it. And that decision can often be complex and emotional.

My research, and that of many others in this field, has shown that as we consider whether to adopt a new belief or behavior, we are guided, much more than we realize, by our social networks. Through the hidden power of social influence, the network around us shapes how we respond to an innovation, causing us either to ignore it or to adopt it. This much-deeper process of social spreading is called complex contagion, and it has given rise to a new science for understanding how change happens—and how we can help make it happen.

When we discuss “social networks,” it is important to remember that these networks are not necessarily digital. They have existed for as long as humans have been around. They include everyone we talk to, collaborate with, live near, and seek out. Our personal network makes up our social world. The science of social networks studies the web that binds these social worlds together—from neighbors living on the same street to strangers on different continents—and how social contagions can spread among them.

This book crystallizes over a decade of new research by myself and hundreds of other sociologists, computer scientists, political scientists, economists, and management scholars working to discover the most effective strategies for spreading complex contagions. But the idea at its heart is a simple one: successful social change is not about information; it’s about norms. Social networks are not merely the pipes through which ideas and behaviors flow from person to person. They are also the prisms that determine how we see those behaviors and interpret those ideas. Depending on how a new idea comes to us, we may either dismiss it or jump on board.

Unlike perceptual bias, in which our eyes distort visual information, or cognitive bias, which distorts our reasoning about economic information, network bias is the way our social networks invisibly shape the beliefs we hold and the norms we follow.

The social network that links the members of a community together can inadvertently reinforce people’s existing biases, preventing innovative ideas and movements from catching on. Yet with slight changes, the same network can instead trigger collective enthusiasm for an innovation, accelerating its adoption throughout the community.

My goal in this book is to help you unravel some of the mysteries of societal transformation by showing you how these social networks function. From protests in the streets to new management strategies in an organization—from the spread of healthy diets to the adoption of solar power—social networks are the force that drives the potential for social change.

In the pages ahead, I will take you to Silicon Valley, where you will see innovations unintentionally crushed by the very “influencers” who are supposed to help promote them.

We will visit Denmark and discover how a clever group of computer scientists deployed a network of autonomous Twitter bots to spawn human social networks that spread social activism to thousands of people.

You will venture behind the scenes at Harvard University, where network scientists pioneered and patented networking strategies to accelerate the adoption of innovative technologies.

Finally, I will show you how President Barack Obama used novel networking strategies to improve the quality of his presidential decisions.

When I began exploring these topics, I worked mostly in the realm of theory, studying the civil rights movement and the worldwide growth of social-media technologies. But a decade or so ago, I realized that if I really wanted to understand why social change succeeds or fails, I would need to find a way to test my theory of networks in the real world. In Parts II, III, and IV of this book, I will detail for you a series of large-scale social experiments I conducted, in which I directly manipulated the behavior of entire populations. Some of these populations were young professionals attending exercise classes at a local gym; others were Democrats and Republicans debating climate change; and still others were physicians engaged in clinical diagnosis. As you will see, these experiments revealed profound new truths about the nature of social change.

By the end of this book, you will understand how the science of networks can empower you to gain control of your own social network and the influence it has on you and others. And you will see how the social networks around you guide people’s behaviors, their receptivity to innovations, and their ability to maintain healthy and productive cultural habits.

In the next chapter, I will begin by identifying popular myths and mistakes in our understanding of social change. But throughout the book, my focus will be on solutions. My ultimate goal in presenting this new perspective on social change is to allow readers from all walks of life to acquire the resources they need to create the change they want to see.




The Myth of the Influencer: The (Un)Popularity Paradox

There is an old joke in brand-marketing circles.

On July 20, 1969, a group of advertising executives stayed late at the office—not because of crushing deadlines but because they wanted to witness a singular moment in history: the first walk on the moon. Along with them, an estimated 530 million people around the world watched Armstrong’s televised image and heard his voice describe the event as he took “one small step for a man, one giant leap for mankind.”

Everyone was in high spirits in celebration of this first-ever event, with the exception of one executive who walked away from the TV, shaking his head. When a colleague caught up with him and asked what was wrong, the executive looked at him sadly and said, “If only Armstrong was carrying a Coke.”

That was the dominant thinking in the late 1960s: sales happened through big, top-down endorsements, traveling to passive audiences via one-way broadcast channels.

Now fast-forward several decades and imagine that you want to launch a new social innovation—a time-management app, a fitness program, a poetry collection, an investment strategy, or a political initiative. You are emotionally and economically invested in your campaign, and you want to ensure it spreads by word of mouth as quickly and as widely as possible. Whom would you choose to promote it: a highly connected social star such as Katy Perry or Oprah Winfrey who resides in the center of a vast social network? Or a “peripheral actor”—someone who is more modestly connected and lives on the network’s fringe?

If you’re like most people, you’ll decide to pitch your change campaign to the social star, rather than the peripheral player.

And you’ll be making a mistake.

The power of highly connected social stars (or, as we now call them, influencers) to spread innovations turns out to be one of the most enduring and misleading myths in social science. It has infiltrated the worlds of sales, marketing, publicity, and even politics. So much so, that even when an innovation spreads from the periphery to achieve worldwide influence, we still give the credit for its success to a social star.

The Oprah Fallacy

When Twitter launched in March 2006, the earth did not move. Its founders and a few early funders were excited about the technology, but the microblogging site was not the immediate blockbuster you might imagine, given that it now has more than 330 million users and has become a wildly popular marketing tool for businesses, nonprofits, and even politicians. Twitter merely crept along in its early months, spreading slowly.

So, what happened to transform it from another also-ran into one of the largest communication platforms in the world?

Twitter looks like the kind of technology that New Yorker writer Malcolm Gladwell and Wharton School marketing professor Jonah Berger refer to as “contagious.” To jump-start Twitter’s growth, in 2007 its founders decided to promote it at the giant annual tech-and-media conference South by Southwest, aka SXSW, in Austin, Texas. SXSW is a weeklong paradise for film, music, and technology buffs who thrive on discovering avant-garde media and quirky new technologies.

Today SXSW is the largest music-and-media festival in the world, with more than fifty thousand annual attendees and talks by leading political and media figures such as Bernie Sanders, Arnold Schwarzenegger, and Steven Spielberg. Back in 2007, however, SXSW was still working its way from the fringe to the mainstream, and cool new technologies like Twitter were often debuted there as a way of doing preliminary market testing. Twitter was a big hit.

After that initial breakout, Twitter grew only incrementally until 2009, when its growth suddenly accelerated. The story commonly told about Twitter’s explosion is that Oprah Winfrey deserves the credit. On April 17, 2009, Winfrey sent her first tweet on her talk show, before an audience of millions. By the end of the month, Twitter had grown to approximately twenty-eight million users.

This version of the Twitter success story is compelling and easy to grasp. It tells us that the key to success is to find the influencers and get them on board. It gives start-ups, and the people who invest in them, a road map for success. And it features a major star.

The problem is that this road map steers us off course. In fact, when it comes to the kinds of change we care about most, it leads to a dead end.

Oprah’s adoption of Twitter was not the reason for Twitter’s success; it was a result of it. By the time Oprah sent her first tweet, Twitter had already entered the fastest part of its growth curve. Starting in January 2009, Twitter was achieving exponential growth month after month, skyrocketing from under eight million users in February to approximately twenty million users in early April. In fact, Oprah adopted at the peak of Twitter’s growth. Afterward the site kept growing, but at a slower rate.

A better question to ask about Twitter’s success is not How did they get Oprah to spread Twitter? but rather How did Twitter grow so big that Oprah herself got a boost from adopting it? The answer to this question explains how small start-up companies, fringe political campaigns, and marginal interest groups can use people’s well-established friendship networks to grow new movements into household names—and it involves the social periphery, not the social stars.

The Aerosmith Gesture

A revealing study conducted in the virtual-reality platform Second Life provides rich insight into how the spread of innovation accelerates when we target networks of peripheral actors—not the Perrys and Oprahs of the world, but our everyday friends and neighbors.

Just as in the real world, commerce has real value in Second Life. That was especially the case when Second Life was in its infancy. In February 2006, only three years after the site launched, a member of the Second Life community, Ailin Gaef (going by the Second Life alias Anshe Chung), earned enough credit inside the game’s fictional economy to cash in her assets for more than one million real-world US dollars. Anshe’s virtual activity had made Ailin into a real-life millionaire.

Thousands of entrepreneurs flocked to Second Life. People wanted to spread the word about their products and services to as many other users as possible—and get rich in the process. Their approach to success was the same as it would be in a real-world market: find the influencers and convert them into evangelists for your idea. In Second Life, as anywhere else, the traditional wisdom is target the highly connected stars in the social network.

There are lots of things to buy in Second Life—clothes, houses, pets, and food, for example. But it goes far beyond that. In Second Life, you can also buy behaviors.

Unlike in real life, if you want to adopt a new style of talking or a hip kind of handshake, you need to make a deliberate effort to acquire it. Sometimes that requires money—as much as $500 US—sometimes it doesn’t. But it always requires some forethought and action.

One gesture that became popular in the fall of 2008 was the Aerosmith gesture, an animation in which your character throws its hands above its head and makes a horn shape with its index and pinky fingers, with its thumb outstretched for emphasis. A gesture like this needs to be officially added to your character’s list of assets in order for you to use it. But the important thing about a Second Life gesture is that you don’t really want to use it unless other people are using it, too.

It’s the same in real life. Imagine greeting a friend at a bar with the Aerosmith gesture just as he extends his hand for a handshake. You’d feel ridiculous.

Given the established norm of shaking hands, how did the Aerosmith gesture become popular? In real life, this would be a difficult question to answer; it would be nearly impossible to trace exactly how many people were greeting their friends and colleagues with handshakes versus how many were using the Aerosmith gesture. In Second Life, however, analysts can not only count the number of players using the gesture, they can track the number of interactions each person has in a given day, see how each interaction transpired, and note from whom each person learned the Aerosmith gesture and at what point they started using it themselves. Which makes Second Life the perfect place to measure how social innovations spread.

In 2008, physicist Lada Adamic and data scientists Eytan Bakshy and Brian Karrer set out to use this digital precision to measure the person-to-person transfer of a new behavior. Conventional wisdom at the time said the first thing to do was to look for the influencers. In Second Life, as in the real world, there are social stars—the Oprahs of the metaverse, who are far more socially connected than everyone else. These people are in a position to exert a lot of social influence on the community. If a new behavior like the Aerosmith gesture is adopted by one of these prominent individuals, you might assume that it would then spread to a lot of other people very quickly.

As it turns out, the researchers found exactly the opposite of what they expected. The most highly connected users were in fact the least effective at spreading the Aerosmith gesture. Why? Surprisingly, because the more connected people were, the less likely they were to adopt the innovation. The more contacts that someone had who were not using the Aerosmith gesture, the less likely they were to make the effort to acquire it, or to start using it themselves.

The value of the Aerosmith gesture, like most assets in Second Life, hinges on its being commonly accepted by other people around you. Just like any greeting gesture—hugging, kissing on the cheek, high-fiving—you do not want to try it out in a new social situation if everyone you know is still shaking hands. You would rather wait until you’re sure the gesture is a well-known greeting before you try it yourself.

Once a new social trend catches on, it’s good to be on the frontier. But you don’t want to adopt too early and be out there all by yourself—the lone high-fiver in a world of handshakers. This is an example of what sociologists call a coordination problem. Any kind of social gesture you might adopt—from a high-five to a handshake—is a behavior that depends on coordinating with other people. The question for the researchers was: how many people must adopt the Aerosmith gesture before you will think the trend is popular enough that you decide to adopt it too? It turns out that the answer is relative: it depends on the size of your social network.

Adamic and her team discovered something that has since been confirmed in dozens of other settings, from Facebook to fashion. Namely, that we are typically influenced by the percentage of the people we know who are doing something, rather than the total number. Imagine you know only four people in Second Life. If two of them start using a new greeting gesture, you would be likely to start using it too. Fifty percent of your social network is a lot of social influence. But if you know 100 people in Second Life, two people adopting a new gesture is unlikely to have much of an effect on your behavior. You’ll wait until you see more people adopting it before you decide to start using it as well.

In fact, the researchers found that a very popular person with about five hundred contacts was about ten times less likely


  • “An utterly fascinating read that will challenge some of your core assumptions about how social change happens. As a leading sociologist and expert on social networks, Damon Centola reveals that if you want to change beliefs and behaviors, influencers are overrated and sticky ideas aren’t always enough—and he explains what really causes the rise of movements and the diffusion of innovations. It might be the most important book on the science of social influence since Cialdini's Influence.”—Adam Grant, New York Times bestselling author of Originals and Give and Take, and host of the TED podcast WorkLife
  • “Damon Centola’s deeply insightful book provides compelling evidence about how change ripples and surges its way through our lives. This is timely must-reading for any leader who wants to meet the forces of resistance head-on and steer behavior in positive directions.”—Rosabeth Moss Kanter, Harvard Business School professor and author of Think Outside the Building: How Advanced Leaders Can Change the World One Smart Innovation at a Time
  • “In Change, Damon Centola brings together decades of research on unexpected ways that social networks create change. If you want to spread ideas and practices, Influencers at the center of a social network who have a large number of loose connections may matter less than overlapping, strongly connected networks located at the periphery. Whether you are introducing a new product or fostering a social movement, Centola’s new book provides fresh insights to guide you toward success."—Harvey V. Fineberg, MD, PhD, president of the Gordon and Betty Moore Foundation
  • “In this moment of history when engrained norms and behaviors are being upended, Damon Centola, the scientist who reshaped our narrative about social change, helps us understand what sticks, and what passes, and how to use this knowledge to foster positive change. Change is a journey that highlights how social networks and norms, together, reshape our society.—Albert-László Barabási, author of The Formula
  • “This remarkable book provides a powerful way to think about change. Damon Centola elegantly synthesizes the latest research from network science, sociology, and psychology into a critically important guide to effecting change in our individual lives, businesses, societies, and beyond.”—Jonah Berger, Wharton Professor and bestselling author of The Catalyst and Contagious

On Sale
Jan 19, 2021
Page Count
352 pages
Little Brown Spark

Damon Centola

About the Author

Damon Centola is a Professor in the Annenberg School for Communication and the School of Engineering and Applied Sciences at the University of Pennsylvania, where he is Director of the Network Dynamics Group. His widely cited work has been published across several disciplines in the world's leading journals, including Science, The Proceedings of the National Academy of Sciences, Nature Human Behavior, The American Journal of Sociology, and Journal of Statistical Physics. His speaking and consulting clients include Amazon, Microsoft, Apple, Cigna, the Smithsonian Institution, the American Heart Association, the National Academies, the U.S. Army and the NBA. Popular accounts of Damon's work have appeared in the New York Times, Washington Post, CNN, Wall Street Journal, Wired, TIME, The Atlantic, and Scientific American.

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