Abstract: New social movements, technologies, and public-health initiatives often struggle to take off, yet many diseases disperse rapidly without issue. Can the lessons learned from the viral diffusion of diseases be used to improve the spread of beneficial behaviors and innovations? In this talk, I discuss several new breakthroughs in the science of network diffusion, and how these advances have improved our understanding of how changes in societal behavior--in voting, health, technology, and finance―occur, and the ways social networks can be used to influence how they propagate. The findings show that the same conditions accelerating the viral expansion of an epidemic unexpectedly inhibit the spread of behaviors. I show how many of the most well-known, intuitive ideas about how social networks function have in fact been responsible for causing past diffusion efforts to fail. I present new findings and new network methods that have been used to enable social change efforts to succeed much more effectively.