The numerous prevention campaigns promoting healthy lifestyles are based on the assumption that people place great importance on their health, feel responsible for it, and are willing to take steps to improve their future health. A national telephone survey conducted in June and July 2008 among a randomly selected sample of 2,000 people aged 18 to 75 examined how prevention campaigns (on tobacco, alcohol, and nutrition) are perceived by individuals and the impact of these campaigns. One in eight French people possesses all the qualities that would make them an ideal recipient of prevention campaigns. These campaigns also elicit mixed reactions: receptiveness, indifference, hostility, mistrust, and anxiety. The results suggest that the perceived credibility of the campaigns appears very high. It is a necessary but not sufficient condition for their effectiveness. The study also shows that the moralizing aspect of the campaigns is not necessarily an obstacle to this effectiveness, but that anxiety is not always an effective way to encourage behavioral change, particularly among the most dependent smokers. More broadly, recent campaigns appear to have had a very significant impact on behavior, at least in the short term. They have been widely shared, especially by those most receptive to them: following these campaigns, many discussed them with loved ones they considered affected. It remains to be seen to what extent such sharing contributes to their effectiveness.