In October 2016, Santé publique France launched the first “Smoke-Free Month” campaign, which challenges smokers to quit smoking for 30 days in November. The effectiveness of this social marketing initiative was assessed using data from the 2017 Santé publique France Barometer, a random telephone survey of 25,319 individuals, including 6,341 daily smokers at the launch of the 2016 “Month Without Tobacco” campaign. Respondents to the 2017 Santé publique France Barometer who had attempted to quit smoking in the last quarter of 2016—whether they were smokers or ex-smokers in 2017—were contacted again one year later to study their smoking behavior over the longer term. The results demonstrate the effectiveness of the 2016 Tobacco-Free Month campaign. Beyond the mere number of participants, this study provides a comprehensive view of the impact of this social marketing initiative, closely aligned with the public health objective of encouraging smokers to quit, regardless of the methods they choose to achieve this.