This study investigates whether recreational boating safety investments and behaviours of current interest are determinants of boating injury severity, and if so, their effects. An ordered probit analysis of 1989-1993 boating accidents suggests that human capital investments in safety, in the form of operator boating experience and formal instruction, reduce both operator and passenger injury severity. Higher levels of operator (passenger) alcohol consumption increase operator (passenger) injury severity, but no relationship was found between operator alcohol consumption and passenger injury severity. At the time a trip is taken, wearing a flotation device has the most efficacious effect on both operator and passenger injury severity. In general, the results support regulatory policies aimed at increasing the use of personal flotation devices as well as reducing alcohol consumption.