We often think social contagion yields negative consequences - teens smoke because other teens smoke, for example. However, in his latest book, UNDER THE INFLUENCE: Putting Peer Pressure to Work, ROBERT FRANK makes the optimistic case that the economics of social contagion could solve our most critical problems \u2014 from climate change to income inequality \u2013 as well as the Covid-19 pandemic. There\u2019s evidence: As VOX\u2019s Ezra Klein points out, in the face of the coronavirus, "social pressure has driven perhaps the single fastest behavioral transformation in human history.\u201d