'Until not much more than 20 years ago, economists frequently lamented the fact that they were limited in their empirical analyses to statistical assessments of market behavior, because controlled economic experiments were (thought to be) infeasible, unethical, or both. Much has changed in the...

We analyze institutional solutions to international cooperation when collective action creates negative externalities and splits the actors into supporters and opponents, all of whom can spend resources toward their preferred outcome. We study how actors can communicate their preferences through...