Between 1972 and 1997 the authors prospectively evaluated injuries reported to the injury clinics at the base lodges of the Sugarbush ski area in northern Vermont. During that time, the number and rate of injuries resulting from self-reported inadvertent releases and failure-to-release incidents resulting in mid-shaft tibial fractures have been tracked. Rates of these two injury modes, in absolute terms mean days between injuries (MDBI) and in relative terms as a percent of all injuries have declined by more than 85 and 75%, respectively. The performance of the ski-binding-boot (SBB) systems have been analyzed in the context of signal detection theory. The simultaneous improvement in system performance in terms of lower injury rates due to both inadvertent release and failure-to-release modes is most likely the result of a variety of intervention measures, such as standardization of ski boot sole configurations, shop practices that require testing before release of the SBB system to the customer, better binding system hardware design that has reduced and controlled friction between the boot and other parts of the system, and empirical research into the dynamic performance of binding systems, the biomechanical strength of the tibia, and the minimum SBB retention requirements.