Cessation television ads are often evaluated with measures of perceived effectiveness (PE) that gauge smokers' reactions to the ads. Although measures of PE have been validated for other genres of public service announcements, no studies to our knowledge have demonstrated the predictive validity of PE for cessation TV ads specifically. We analyzed data from a longitudinal Web survey of smokers in the United States to assess whether measures of PE for cessation TV ads are causally antecedent to cessation-related outcomes. These data consisted of baseline and 2-week follow-up surveys of 3,411 smokers who were shown a number of cessation TV ads and were asked to provide their appraisals of PE for those messages. We found that baseline PE for the ads was associated with increased negative feelings about smoking, increased outcome expectations about the benefits of quitting, increased consideration of the benefits of quitting, increased desire to quit, and increased intentions to quit smoking at follow-up. Results suggest that measures of PE for cessation TV ads can be powerful predictors of likely ad success. Hence, our findings support the use of PE in quantitative ad pretesting as part of a standard regimen of formative research for cessation television campaigns.