A framework for engineering word-of-mouth and making products, ideas, and content contagious. Based on Jonah Berger's research into why certain things catch on while others languish in obscurity — and how to systematically tip the odds in your favor.

Virality is not born — it is engineered. Products don't go viral by luck or by simply being great. They spread because they were designed — consciously or unconsciously — to be shared.

The foundation: Contrary to popular belief, only 7% of word-of-mouth happens online. The remaining 93% happens offline, in everyday conversations. This means virality isn't just about social media — it's about understanding the psychology of why people talk about and share certain things. Sharing follows predictable psychological patterns, and these patterns can be engineered into any product, idea, or piece of content using the STEPPS framework.

Goal: 10/10. When reviewing or creating products, campaigns, content, or features for shareability, rate 0-10 based on adherence to the STEPPS principles below. A 10/10 means the offering activates all six STEPPS drivers; lower scores indicate untapped viral potential. Always provide the current score and specific improvements needed to reach 10/10.

Six principles that make things contagious:

S - Social Currency     → Does sharing it make people look good?
T - Triggers            → Is there an environmental cue that reminds people of it?
E - Emotion             → Does it evoke high-arousal feelings?
P - Public              → Is it visible when people use or consume it?
P - Practical Value     → Is it genuinely useful information people want to pass along?
S - Stories             → Is it wrapped in a narrative people want to tell?

Not a checklist — a multiplier. Each principle independently increases the likelihood of sharing. The most contagious ideas activate multiple STEPPS simultaneously. But even activating one or two well can dramatically increase word-of-mouth.

Core concept: People share things that make them look good — smart, cool, in-the-know. If your product or idea makes people feel like insiders, they'll spread it to boost their own image.

Why it works: We use brands and information as social signals. Sharing remarkable facts, exclusive access, or high-status products is a form of self-enhancement. People don't just share what they think — they share what makes them look good for thinking it.

Ethical boundary: Social currency should make people genuinely feel good, not manipulate through false scarcity or manufactured exclusivity that breeds toxicity. Create real insider value, not artificial gatekeeping.

See: references/social-currency.md for remarkability exercises and game mechanics design.

Core concept: Top-of-mind means tip-of-tongue. Environmental cues — sights, sounds, smells, times of day, routines — can trigger people to think about and talk about your product. The more frequently people encounter your trigger, the more they'll talk about you.

Why it works: Most word-of-mouth is not driven by excitement about the product itself but by whatever happens to be top-of-mind at the moment of conversation. If your product is linked to a frequent environmental cue, it gets mentioned more often — not because it's more exciting, but because it's more accessible in memory.

Ethical boundary: Triggers should create genuine, helpful associations. Hijacking sensitive contexts (grief, health scares) as triggers is manipulative and will backfire.

See: references/triggers.md for habitat analysis and trigger design frameworks.

Core concept: When we care, we share. High-arousal emotions — both positive (awe, excitement, amusement) and negative (anger, anxiety) — drive sharing. Low-arousal emotions (sadness, contentment) suppress it.

Why it works: Physiological arousal — the racing heart, the tightened muscles, the activated state — creates a need to share. It's not about positivity vs. negativity; it's about activation vs. deactivation. Content that fires people up gets shared; content that brings people down gets ignored.

Ethical boundary: Anger and outrage are high-arousal and highly shareable, but engineering outrage for clicks corrodes trust. Use high-arousal negative emotion sparingly and only when the underlying cause genuinely warrants it.

See: references/emotion.md for emotional arousal mapping and content audit tools.

Core concept: Built to show, built to grow. If people can see others using your product, they're more likely to adopt it themselves. Make the private public — design for observability.

Why it works: People imitate what they can see. If your product usage is invisible, you lose the most powerful adoption channel: social proof through observation. The phrase "monkey see, monkey do" exists because observational learning is one of the deepest human instincts.

Ethical boundary: Public visibility should empower users, not shame them. Never make private information (failures, health data, financial struggles) involuntarily public. The user should always control what is visible.

See: references/public-visibility.md for observability design and behavioral residue strategies.

Core concept: People share useful information to help others. News you can use spreads — especially when it's packaged in a way that's easy to pass along and clearly valuable.

Why it works: Sharing practical value is driven by altruism — people genuinely want to help their friends and family. If your content or product saves people time, money, or effort, they'll share it as a favor to their network.

Ethical boundary: Practical value must be genuine. Fake savings (inflated "original" prices), misleading tips, or clickbait "life hacks" that don't actually work will destroy trust faster than they generate shares.

See: references/practical-value.md for Prospect Theory applications and knowledge packaging formats.

Core concept: People don't just share information — they tell stories. The best way to spread your idea is to embed it inside a narrative so engaging that people retell it, and your brand comes along for the ride. This is the Trojan Horse approach.

Why it works: Stories are how humans naturally process and transmit information. We think in narratives, not bullet points. A well-crafted story carries your brand message inside it like a Trojan Horse — the listener absorbs the message while being entertained by the story.

Ethical boundary: Stories must be true or clearly fictional. Fabricating testimonials, inventing origin stories, or creating misleading narratives will eventually be exposed, destroying the brand's credibility and making future word-of-mouth toxic.

See: references/stories-trojan-horse.md for narrative templates and the Trojan Horse integration test.

The STEPPS principles are most powerful when combined. Here are applied combinations for common scenarios:

Run this diagnostic on any product, campaign, or content piece:

Jonah Berger is a marketing professor at the Wharton School at the University of Pennsylvania. His research focuses on social influence, word-of-mouth, and why products, ideas, and behaviors catch on. He has published dozens of articles in top-tier academic journals and his work has been featured in the New York Times, Wall Street Journal, and Harvard Business Review. "Contagious" distills his years of research into a practical framework for understanding and engineering virality. He has also authored "Invisible Influence" (on how hidden forces shape behavior) and "The Catalyst" (on how to change minds), and consults with companies ranging from startups to Fortune 500 firms on how to make their products and ideas spread.