In 1996/97, the first season of openly professional rugby union was played in England. For many of the clubs which opted to become involved in the professional game, this was the end of an era. In some cases, over 100 years of institutionalised amateur practice was brought to an end, and professionalism became the dominant mode of operation in these organisations. In order for those clubs which chose to professionalise to operate effectively, the values and related organisational structures which were the very essence of amateurism, had to be deinstitutionalised. Deinstitutionalisation is the erosion or discontinuity of organisational activities and practices, which through the force of habit, tradition, or history, have come to be accepted as legitimate. This paper provides a case study analysis of the process of deinstitutionalisation as it occurred in one Premiership rugby union club. Using data collected through a series of semi-structured interviews conducted with both the adherents of amateurism and the proponents of the new professional organisational structure, this paper identifies some of the forces that contribute to deinstitutionalisation. Following Oliver's (1992) theoretical lead, we empirically show how political, functional, and social pressures contributed to the process of deinstitutionalisation, and how these are mediated by inertial and entropic organisational forces. We also extend Oliver's analysis by showing the way in which the manipulation of organisational symbols can play a role in the dynamics of deinstitutionalisation.