This research evaluated the impact of a peer education smoking prevention program among students, the beneficiaries, and professionals from different sectors operating in the program's environment and involved in the program. The evaluation approach drew upon concepts from the sociology of organizations. A survey was carried out using semi-structured interviews conducted with stakeholders involved in the project. The analysis of the survey's results revealed a number of changes having taken place, such as the disturbing effects of power strategies, positive changes in students' relationship to smoking and their ability to contribute as peers to its prevention, as well as unexpected changes generated by the program in terms of the professional practices of stakeholders.