Can evolutionary design of social networks make it easier to be ‘green’?

•Engagement of a large public in domestic conservation actions can have a large impact.•New gains can be made using the Web to build support for environmental stewardship.•Evolutionary and social psychology tell us how to generate cooperation the Web.•Combining social networking with citizen-mapping can harness the power of the crowd.•Communications fostering group-identity or group-efficacy can motivate people to act.•Visibility of actions, norms, reputations, and benchmarks can increase cooperation. The social Web is swiftly becoming a living laboratory for understanding human cooperation on massive scales. It has changed how we organize, socialize, and tackle problems that benefit from the efforts of a large crowd. A new, applied, behavioral ecology has begun to build on theoretical and empirical studies of cooperation, integrating research in the fields of evolutionary biology, social psychology, social networking, and citizen science. Here, we review the ways in which these disciplines inform the design of Internet environments to support collective pro-environmental behavior, tapping into proximate prosocial mechanisms and models of social evolution, as well as generating opportunities for ‘field studies’ to discover how we can support massive collective action and shift environmental social norms.