How does environmentalism square with traditions regarding security? This book offers a political sociology of the emergence and proliferation of ecoterrorism. The question posed here is not what should be done about the problem of individuals or groups who come to use violent means in support of their pro-environmental beliefs, but rather what is likely to be done given the nature of the ideological battleground and the available countering methods. Ecoterrorism is presented as an instance of tactics from the point-of-view of social movement theory (SMT), and as a problem for social and political ordering from the point-of-view of critical security studies.