Collective action involves collaborative efforts in groups that diverge from social norms. There are two main theories of collective action. Convergence theory holds that collective action occurs when people with similar ideas gather in one place. Emergent norm theory emphasizes the influence of leaders in promoting new norms that group members then follow. The passage also notes that while Americans have traditionally had high levels of volunteerism, it seems to have declined somewhat with the rise of the internet, as people can now join groups and donate online without face-to-face interaction.