In New Zealand (NZ), the Accident Compensation Corporation (ACC) has developed a pre and post-implementation cost-outcome formulae for sport injury prevention to provide information regarding the success of a prevention programme. The ACC provides for the cost of all personal injuries in NZ and invests in prevention programmes to offset 1.6 million annual claims that cost $NZD 1.9 billion. The ACC invests in nine national community sport injury prevention programmes that represent 40% of sport claims and costs. Pre-implementation is used to determine the decision whether to invest in implementation and to determine the level of such investment for the injury prevention programme. Post-implementation is calculated two ways: unadjusted, assuming ceteris paribus; and adjusted assuming no prevention programme was in place. Post-implementation formulae provide a return on investment (ROI) for each dollar invested in the programme and cost-savings. The cost-outcome formulae approach allows ACC to manage expectations of the prevention programme as well as when it will provide a ROI, allowing it to take a long-term view for investment in sport injury prevention. Originally developed for its sport injury prevention programmes, the cost-outcome formulae have now been applied to the other prevention programmes ACC invests in such as home, road and workplace injury prevention.