Political protests cannot succeed without public support. Extant studies point to weaker average support among ideological conservatives, but researchers have yet to consider the extent to which such apparent ideological asymmetry is (a) an artifact of the particular protest cases that researchers have tended to investigate, and/or (b) conditioned by the precise meaning of “ideological conservatism.” In this investigation, we address these gaps. Specifically, we analyze public perceptions of protest legitimacy after exposing survey respondents to one of a series of experimental treatments that randomize the specific ideological and issue contents of the particular protests under consideration. In iterative models, we observe how political ideology, social dominance orientation and authoritarianism condition the effects associated with these experimental treatments. The data suggest that that the notorious ideological asymmetry that is often associated with support for protests is authentic, but it is also conditioned in important ways by these other factors.