Contagious Book Summary: Why Things Catch On by Jonah Berger

Much like the book Hooked by Nir Eyal, in the book, Contagious Jonah Berger dives deeper into psychology to explain why certain products, services, and brands perform better than others. Jonah Berger, a marketing professor at Wharton University is a New York Times Bestseller and has authored many articles and books on consumer choice and proven marketing methods.

This post is a summary of the book Contagious: Why Things Catch on, highlighting the best concepts and ideas we have got from reading it and we are also going to tell you whether it is worth reading the complete book.

Contagious book summary

Contagious is a book that explains the seemingly unexplainable, takes difficult concepts, and makes them simple. His methods explain why trends, both online and offline, go viral and is at the top of everyone’s mind for some time.

contagious why things catch on book summary -Jonah Berger

Since the age of our prehistoric ancestors, humans explained the world through stories, and then shared them with others. The more popular the story, the further it spread. Once stories spread beyond their local destination, others would start to put their poetic spins and changes to make the tale more grandiose.

In the modern age, this is much easier to do. With social media, instant feedback can be given through likes and comments. Further, they can be shared with a click of a button or the paste of a link.

The internet’s most popular “poetic spin” on these tales is creating memes, which are viral concepts that usually is created satirically from the original. Berger attempts to explain in this book why some trends and ideas go viral, and others do not – and tries to make sense of the seeming randomness of videos and pictures going viral on the internet.

Best ideas from Contagious summarized

Here are some of the best ideas and concepts from Contagious summarized.

Organic Growth Is The Best Marketing Method

There are a plethora of ways to grow your brand and market yourself. The most difficult part in regards to marketing is launching. No one knows who you are, and even if you are a master at your craft, no one will come and buy from you. Many businesses fail because they dive deep in paid advertising or buy a large supply of promotional materials (business cards, flyers, printed merchandise, etc) when they don’t need to.

The best example to the following point would be a contractor that gets hired to do some renovation work in a suburban neighborhood. No matter what that contractor is working on, it always seems that neighbors will approach them for a quote or to get their information.

The contractor knows that if they do a good job on a house and the street is there to see it, they will most likely get more clients. No social media was used.

It is with this example that we can solidify Jonah’s point; The most powerful marketing tool is word of mouth and not social media. Social media is just that: a medium where others can interact and share. Word of mouth is important because of two things:

  1. People trust their friends and family many times more than they trust advertisements
  2. Word of mouth targets your ideal customer, relatives only refer you to others if they are having the exact problem, and are more likely to close.

Marketers Should Endeavour To Be “Top-of-mind”

In this section, Berger links two sayings together: “Top of mind, means the tip of the tongue”. Berger explains that to have a viral concept, there must be at least one common trigger for viewers to get excited about and remain at the front of their minds indefinitely. For example, there are a series of popular commercials that went viral about the Trivago company.

Trivago is one of many companies that assists users in finding hotels and vacation packages. At the end of each commercial, they would add “Hotel?: Trviago” or any variation. A popular meme that is still seen today exists where users list certain pain points, and then end them with the above phrase, such as:

Can’t sleep: drink warm milk

Keep waking up: meditate before bed

Hotel: Trivago

A seemingly nonsensical addition to a list, usage of the Trivago site soared pre-pandemic. You also cannot forget the popular music video “Friday” by Rebecca Black. Notoriously known for a hilariously poorly made video and production, it went viral due to the trigger word “Friday” where users kept coming back every Friday to watch the video, see the people partying, and then engaging in comments with others about the video.

A marketer’s job at any stage is finding the mechanism of thought that will spark the next big idea that will go viral. When attempting to do this, remember to never force anything, always keep it simple and as history, shows, a low budget does not take away from your message.

Stories Paint A Better Picture

It is estimated that people began telling stores when the fire was invented. The time people went to bed was extended by a few more hours as work could get done by firelight.

The warmth of the fire drew people together, and stories began: about hunting, about adventures in the world, and parables that were cautionary tales to learn something. As mentioned in the summary, stories are still the best way people know how to explain the world. Viral stories became myths and grand tales of success that may even contain larger-than-life concepts. Some are still alive and well today, such as Homer’s Illiad.

The most memorable part about stories aren’t the most entertaining, but the ones that contain a message to be deciphered, or even an evident word of caution. Jonah places a huge emphasis on this section of the book as there are many anecdotes and examples to explain this concept.

Contagious review and Should You Read the complete book?

Contagious is light and entertaining, and it is very easy to read. It takes a difficult question and answers it very simply. Of course, entrepreneurs, small businesses, and influencers can only dream of creating something viral that will launch their next idea or brand.

Veteran and beginner marketers alike can take something from this book. While reading it, don’t forget that other marketing styles are still relevant and their respective methods should also be researched by a reputable thought leader. For example, paid advertisements may not work at first, but once you have a concept, it’s like adding gasoline to a fire.


Contagious is more than just a marketing book, it attempts to shift the world’s view on spreading messages. Even Gary Vaynerchuk, one of the most popular global thought leaders on marketing believes that “marketing is just where attention is”. Similar concepts are found in Berger’s book, and the reader begins to see that effective marketing, is just psychology. The more you study consumer habits, the more success you will have. Start your journey today with Contagious: Why Things Catch On

Marilyn Nissen
Written by Marilyn Nissen

Marilyn Nissen is the founder of, a highly reputable book summary and reviews website. With over a decade of experience in summarizing and reviewing books, Marilyn is a trusted authority in the book industry.