Contagious: Why Things Catch On

In an age saturated with advertising, the most powerful form of marketing remains the oldest: word-of-mouth. Jonah Berger’s Contagious dismantles the myth that virality is a mysterious, digital-age accident or the sole province of massive advertising budgets. Instead, he posits that social transmission is governed by a predictable, analyzable set of psychological principles. Drawing on a decade of rigorous research into everything from New York Times articles to everyday consumer products, Berger argues that whether something catches on is less about luck and more about a specific, replicable design.

Through a series of compelling case studies—from the unlikely popularity of a high-end steakhouse’s cheesesteak to the staggering shares of a blender demonstration video—Berger identifies and elucidates six foundational principles, encapsulated in the acronym STEPPS. These are Social Currency, Triggers, Emotion, Public, Practical Value, and Stories. Each chapter dissects one principle, demonstrating how it functions as a cognitive and social lever. For instance, the principle of Triggers explains why we talk more about a brand linked to a daily routine than a more emotionally resonant one, while Public explores how observable behaviors create self-perpetuating cycles of adoption.

The book moves beyond mere academic observation to provide a practical framework. It translates complex behavioral science into actionable strategies for crafting messages, designing products, and structuring policies that people naturally want to share. Berger shows how subtle tweaks in presentation, from highlighting remarkable inner qualities to building narratives around utility, can dramatically increase an idea’s infectious potential.

Contagious is ultimately a treatise on human social psychology as much as it is a marketing manual. Its insights are relevant for entrepreneurs, policymakers, educators, and anyone seeking to understand the mechanics of cultural influence. By demystifying what makes ideas resonate, it provides a crucial toolkit for navigating and shaping the modern landscape of attention, where peer validation has decisively outpaced corporate messaging in driving what we value and discuss.

The critical consensus praises the book’s accessible framework and actionable, research-backed insights, finding the STEPPS model immediately useful for marketers and entrepreneurs. However, a significant contingent critiques the content as overly simplistic, arguing that the principles are repackaged commonsense rather than groundbreaking discovery. Some readers also note that the heavy reliance on consumer product case studies can feel repetitive and limits the book’s perceived depth, leaving them wanting more nuanced application beyond commercial contexts.