The role of counterfactual thinking as an effective antismoking communications strategy is examined. Specifically, this study investigates how various types of counterfactual thoughts, generated in response to a detrimental smoking scenario, impact individuals' affective evaluations of the scenario, as well as their willingness to participate in a smoking-related behavioral test, a lung-capacity test. This is tested in three experiments, which differ in the timing of gathering individuals' willingness to participate in the lung-capacity test. Experiment 1 collected individuals' willingness to participate in the test shortly after the counterfactual task, whereas Experiments 2 and 3 made this assessment 2 and 7 days following the counterfactual task (respectively). The results of all three experiments indicated that although upward counterfactuals had a negative impact on individuals' affective evaluations of the scenario, they had no effect on participants' willingness to schedule a lung- capacity test. Alternatively, additive counterfactuals did have a significant impact on individuals' preparative actions, despite having no influence on their affective evaluations. This effect, however, decreased with time. By demonstrating that counterfactual thinking may significantly influence smoking-related behaviors, this study's findings contribute to and extend prior counterfactual and antismoking research. © 2003 Wiley Periodicals, Inc.