Background: France’s first month-long alcohol-free challenge, “Le Défi de Janvier – Dry January,” took place in January 2020. A qualitative post-test was conducted to identify the barriers and enablers to participation and success in the challenge. Methods: Individual and group interviews were conducted in February 2020 with registered participants (n = 22), non-registered participants (n = 25), and non-participants (n = 24). The sample was designed to ensure a diversity of profiles. Results: Participants’ motivations stem from individual factors (questioning one’s consumption, testing one’s ability to abstain, adopting a healthier lifestyle) and collective factors (encouraging a loved one, for fun), leading to varying levels of commitment. This translates into distinct usage patterns and needs, modeled in a typology. Barriers and drivers to participation (feeling personally affected, social cost, anticipated stigma versus perceived benefits, sense of self-efficacy) and to the success of the challenge (social pressure versus support) are described. Discussion: Suggestions for improvement are offered, such as the need for media coverage of the challenge and the development of support tools best suited to participants’ experiences and profiles.