Today Twitter will begin testing such an idea: that showing an internet platform’s rules to users will improve behavior on that platform. Social norms, which are people’s beliefs about what institutions and other people consider acceptable behavior, powerfully influence what people do and don’t do. Research has shown that when institutions publish rules clearly, people are more likely to follow them. We also have early evidence from Nathan’s research with reddit communities that making policies visible can improve online behavior. In an experiment starting today, Twitter is publicizing its rules, to test whether this improves civility.