A metacognitive model (MCM) is presented to describe how automatic (implicit) and deliberative (explicit) measures of attitudes respond to change attempts. The model assumes that contemporary implicit measures tap quick evaluative associations, whereas explicit measures also consider the perceived validity of these associations (and other factors). Change in explicit measures is greater than implicit measures when new evaluative associations are formed and old associations are rejected. Implicit measure change is greater than explicit when newly formed evaluative associations are rejected. When implicit and explicit evaluations conflict, implicit ambivalence can occur. The authors relate the MCM to the associative-propositional evaluation model and explain how the MCM builds on the attitude strength assumptions of the elaboration likelihood model of persuasion.