The effect of a persuasive communication on individuals' attitudes can be influenced by the cognitive behavior they have performed in an earlier, unrelated situation. Inducing participants to make supportive elaborations about a series of propositions activated a bolstering mind-set that increased the effectiveness of an unrelated advertisement they encountered subsequently. However, inducing participants to refute the implications of a series of propositions activated a counter arguing mind-set that decreased the ad's effectiveness. These mind-sets had more impact when the cognitive behavior they activated differed from the behavior that would occur in the absence of these mind-sets. When the implications of a persuasive message were difficult to refute, inducing a counter arguing mind-set increased its effectiveness. Finally, watching a political speech or debate activated different mind-sets, depending on participants' a priori attitude toward the politicians involved, and these mind-sets influenced the impact of an unrelated commercial they considered later.