Book profile
Contagious: Why Things Catch On
Jonah Berger
Products, ideas, and behaviors catch on not because of luck or special people, but because they embody six shareable qualities captured in the STEPPS framework.
Why do some products, ideas, and behaviors become popular while most fail? Wharton marketing professor Jonah Berger argues that virality is made, not born, and that the secret lies in understanding the psychology of why people talk and share. Drawing on years of rigorous research analyzing thousands of New York Times articles, baby names, car purchases, and word-of-mouth campaigns, Berger distills six principles—Social Currency, Triggers, Emotion, Public, Practical Value, and Stories (STEPPS)—that make content contagious. With memorable examples from a hundred-dollar cheesesteak to blending iPhones to viral Google ads, Contagious gives marketers, entrepreneurs, nonprofits, and anyone with a message a practical, science-based toolkit for engineering word of mouth and making ideas spread.
The model
A framework explaining how six design levers (Social Currency, Triggers, Emotion, Public, Practical Value, Stories) influence psychological and behavioral states that drive social transmission and the popularity of products, ideas, and behaviors.
Frameworks you can use
- Social Currency: people share things that make them look good.
- Triggers: top of mind leads to tip of tongue; frequent environmental cues drive talking.
- Emotion: when we care, we share; high-arousal emotions kindle the fire.
- Public: built to show, built to grow; observability enables imitation.
- Practical Value: news you can use; people share useful information to help others.
- Stories: information travels under the guise of idle chatter via Trojan-horse narratives.
Key terms
- Social Currency
- The reputational benefit people derive from sharing a product or idea that makes them appear smart, cool, or in-the-know to others.
- Triggers
- Environmental stimuli that act as reminders, bringing a related product or idea to mind and prompting people to talk about it.
- Emotion
- The feelings evoked by a product, idea, or message, varying in valence and physiological arousal.
- Physiological Arousal
- A state of bodily activation and readiness for action that drives the impulse to share.
- Public Observability
- The extent to which use or adoption of a product, behavior, or idea is visible to others.
- Practical Value
- The usefulness of information for helping the recipient save time, money, or improve experiences.
- Stories
- Narratives that embed and carry information or brand messages, making them shareable as idle chatter.
- Valuable Virality
- The degree to which the brand or message is so integral to a story that it cannot be told without mentioning it.