Building on recent work exploring metacognitive factors in minority/majority influence, three studies tested the hypothesis that when people receive persuasive messages from sources in the minority or majority, their attitude certainty can be determined by the extent to which source status and perceived argument quality match or mismatch. In Study 1, participants were presented with strong or weak arguments from a minority or majority source. Minority condition participants reported greater attitude certainty when arguments were weak rather than strong. Majority condition participants showed the opposite effect. Study 2 replicated this interaction using a manipulation of perceived rather than actual argument quality. In Study 3, these effects only emerged when message recipients’ processing motivation was high. Taken together, the results suggest that attitude certainty can be high or low following minority or majority messages, depending on processing motivation and message recipients’ assessments of other persuasive evidence.