Anti-genetically modified (GM) food organizations have often incited consumers to boycott conventional groceries and donatemoney to their cause. Using telephone survey data from 1008 Canadians, this study examines differences in attitudes, beliefs, knowledge and behaviours of anti- GM food activists and non-activists, then uses multivariate probit analysis to determine which of these characteristics predict the likelihood of such active participation in the anti-GM movement. Food production knowledge and general concerns about health and the environment did not predict anti-GM activism, while anti-corporate sentiments, fear of globalization and belief that GM foods are fundamentally unnatural had the greatest predictive power. (C) 2005 John Wiley & Sons, Ltd.