Background Smoke-free campuses (SFC) prohibit smoking and vaping on all university grounds and for all users. Despite their effectiveness in reducing smoking prevalence, passive smoking, and denormalizing tobacco use, the complex interplay between the programme activities and their impact on users and campus environments remain unclear. This study aims to improve our understanding of the transformation processes associated with SFC expected outcomes. Methods We conducted a retrospective qualitative study on the first SFC implemented in France by the EHESP School of Public Health. Guided by Mayne’s theory of change framework that includes ten dimensions of an impact pathway (e.g. activities, reach/reaction, capacity, behaviour changes, etc.), the research examined the chain of effects and hypotheses driving this SFC. Our dataset included internal documents (e.g. minutes of meetings, administrative documents) and semi-structured interviews with stakeholders (n = 16) involved in the development and implementation of the analysed SFC. Data is currently being analysed. Results Initial results suggest that the EHESP’s SFC activities included communication initiatives, student ambassadors, cessation support for smokers, installation of smoking shelters on campus periphery, etc. These activities were geared on capacity change (e.g. securing support and compliance among campus users, reduce smoking opportunities, promoting the use of cessation aids) and were intended to drive behaviour change (reducing smoking and facilitating cessation among students and staff). The goal of this SFC was not only to impact behaviors but also to educate future health service managers at EHESP to implement SFC policies and set an example for other institutions in France. Conclusions This study identifies some of the transformations that activities of the EHESP’s SFC can generate in students and staff in order to fulfil its outcomes. It also highlighted its expected impact on other institutions. Key messages • Understanding how a smoke-free campus generates its changes is essential in facilitating transferability of experiences to other universities. • Smoke-free campus policies can also generate a broader impact on other institutions.