In this paper, we develop the concept of clandestine legitimacy work as an extension of organizational legitimacy analysis. Mobilizing the recent developments of legitimacy studies, especially on legitimacy judgment and legitimacy work, we suggest that actors are setting up an on-going dialogue on the validity and the propriety of a given legitimacy objects. We also demonstrate the role of the social and the symbolic dimensions and of the day-to-day activities have on this work. We draw on a case study built from ethnographic data collected during the World Equestrian Games in 2014. We particularly focused our analysis on the roles performed by actors, who had different positions but shared something in common: passion of the sport horse. This allowed us to highlight the processes throughout which the rules imposed by actors are reworked. This confrontation led to a clandestine legitimacy work through which actors defined a consensus emerging over the prescriptions of the status.