Objectives This study addresses differences in the predictors of participation in different forms of protest activity using nationally representative data. The two types of protest examined, referred to as conventional and unconventional forms of activism, are differentiated by differing levels of risk, demands, and political legitimacy. Methods The analysis uses multinominal logistic regression and data from the World Values Survey to assess the effects of a wide range of independent variables on participation in protest. Results The results indicate that participation in conventional forms of protest, activities that are relatively undemanding, socially legitimate, and low risk, tend to follow patterns that are consistent with participation in institutional politics. That is, participants in this form of activism tend to be socially privileged and ideologically moderate. Participants in unconventional protest, those that are highly demanding, socially illegitimate, or carry substantial risks, tend to be more ideologically extreme, socially disadvantaged, and more alienated from the conventional political system. Conclusions The findings in this study suggest that the lack of consistency in some existing research on protest participation may be attributable to differences in the predictors of participation associated with different forms of protest. This study indicates that protest participation is not a unitary construct and should not be treated as one in research.