The present research proposes a metacognitive framework for understanding resistance to persuasion. It is suggested that when people resist persuasion, they can become more certain of their initial attitudes. Several experiments demonstrated that when participants resisted persuasion, attitude certainty increased, but only when the attack was believed to be strong. For attacks believed to be weak, certainty was unchanged. It was also demonstrated that attitude certainty only increased when people actually perceived that persuasion had been resisted. This increased certainty was shown to have implications for resistance to subsequent attacks and the correspondence between attitudes and behavioral intentions, These findings suggest that when people perceive their own resistance, they form inferences about their attitudes that adjust for situational factors.