The present investigation evaluated affective style in terms of anxiety sensitivity, emotional reactivity, and distress tolerance in heavy smokers. Specifically, heavy smokers (> or = 20 cigarettes per day) were partitioned into those who were able to quit for at least 7 days (n = 10) and those who were able to quit for less than 7 days (n = 12). All participants completed measures of anxiety sensitivity and maximum breath-holding duration and then were exposed to a 20% carbon dioxide-enriched air challenge. Results indicated that heavy smokers who had not been able to remain abstinent from smoking for at least 1 week during a quit attempt demonstrated significantly greater cognitive-affective reactivity to the challenge relative to their counterparts but did not differ at a physiological level of analysis. Contrary to our hypotheses, neither anxiety sensitivity scores nor maximum breath-holding duration significantly differed between the groups. These findings are discussed in relation to better understanding affective style among heavy smokers.