There is no substitute for direct protection of species and ecosystems. But unless growth in human numbers and material consumption is checked, direct protection will become impossible. Conservation biologists and conservation advocates do not by themselves possess the political resources necessary to achieve adequate direct protection or to check growth. There are many other constituencies, however, whose interests are threatened by growth. Conservation biologists should develop alliances with these constituencies to create a social force that can bring to bear the necessary pressure to change government, corporate, and individual behavior. Building such alliances requires more than traditional forms of education and outreach. It requires reaching people at the deepest levels of culture and personality. Conservation biologists can and should play a role in mobilizing support for conservation through better informed and more carefully crafted outreach.