Rugby Union football is a very popular sport in New Zealand but of all the major sports played in that country, it has the highest reported incidence of injury. In 1995, a national rugby injury prevention program was instigated to address this problem. Known as Tackling Rugby Injury, this multifaceted program was implemented over a five-year period. The program was based on the results of a prospective cohort study of rugby injury, known as the Rugby Injury and Performance Project (RIPP), and was organised around seven themes, five relating to the prevention of injury: coaching, fitness, injury management, tackling, and foul play, and two relating to the implementation and evaluation of the program. The purpose of this paper is to describe the lessons learned from the implementation of Tackling Rugby Injury. Qualitative research methods were used to describe the process of implementation, including informant interviews, participant observation, and the scrutiny of written, visual and archival material. Among the lessons learned were the importance of basing injury prevention strategies on scientific evidence rather than popular belief, the difficulty in implementing complex interventions, the advantages of a formal agreement between partners in the implementation of a program, the central role played by coaches in promoting injury prevention strategies, and the value of describing the process of implementation as well as monitoring injury outcomes and changes in knowledge, attitudes and behaviour. It is hoped that other sports wishing to develop injury prevention programs can learn from this experience.