Why do some products get more word of mouth than others? Why do some ads or messages go "viral"? And how can companies use these insights to help their products and ideas catch on? This workshop brings together researchers and practitioners to talk about the science and application of word of mouth and online content sharing. Sinan Aral (New York University) will discuss whether and when observed statistical relationships can be interpreted as causal peer influence in social networks to better understand the spread of products, political views, and public health behaviors through society. Jonathan Perelman (VP, Agency Strategy and Business Development, BuzzFeed) will demonstrate how the social news organization uses such understanding of social transmission to amplify diffusion of their content. Finally, Jonah Berger (Wharton) will lead a session on how to generate word of mouth and viral content. Based on his New York Times bestseller, Contagious: Why Things Catch On, Berger will describe six principles that lead to all sorts of things—from consumer products to YouTube videos—to catch on and become popular. He will conclude with a set of specific, actionable techniques for designing messages, advertisements, and information that people will share.