For the above challenges to be met, it will be important for the field of injury epidemiology to move from the largely descriptive studies that have predominated in the literature to the application of more rigorous analytical methods for defining the underlying casual patterns of injury. Studies focusing on the descriptive epidemiology of injury have and will continue to serve the field well, perhaps even more so than in other fields, since the proximal etiology of injuries (i.e., acute exposure to physical agents such as mechanical energy) is well known. However, major new advances in the prevention of injuries will continue to require a more analytical approach to understanding the complex array of factors that influence the incidence, severity, and outcomes of injury. At the same time, it will be important for investigators in this field to conduct rigorous evaluations of new interventions to better inform the establishment of programs and policies. These evaluations must include assessments of both the effectiveness and the costs of the intervention. For example, in a recently published systematic review of 10 different strategies for preventing motor vehicle injuries, 54,708 papers and reports were identified in the literature but only 161 met the initial screening criteria for inclusion in the published review (44). Of these, a much smaller number were randomized controlled trials or well executed controlled time series trials. Major advancements in the prevention and control of injuries will continue to rely on effective collaborations between epidemiologists and scientists from other disciplines, including the behavioral sciences, sociology, criminology, law, engineering, and biomechanics. Only through truly collaborative efforts across these disciplines will we be able to establish a foundation for cost-effective interventions. For example, understanding the principles of injury mechanics and the physical and physiologic responses of the human body to the impact of injury is fundamental to the study of injury causation (6). While significant advances have been made in this regard, more work needs to be done. The biomechanics of head injury are still not well understood, yet head injuries account for nearly 50 percent of all injury deaths and remain the leading cause of both injury death and disability among children and young adults. Animal and human cadaver research combined with rapidly evolving techniques of computerized modeling will continue to play a critical role in increasing our understanding of injury mechanisms. At the same time, the development of effective interventions is dependent on a better understanding of the role of behavior in injury causation and prevention (45). We know, for example, that the use of personal protective devices such as seat belts, car seats, and bicycle helmets reduces injury risk and that these behaviors can be influenced through educational, behavioral, and legislative strategies (46-49). Interventions addressing individuals at risk can be enhanced by additional research into risk perception, risk-taking, and behavioral responses to safety improvements. However, behavioral strategies may also be used effectively with key decision-makers who design and manufacture products and who pass and implement laws that affect the injury risk of entire populations; more research is needed to understand and influence the process of behavior change in these groups (50). The importance of injury as a major public health problem worldwide was highlighted in the seminal report "The Global Burden of Disease" (25). Worldwide, injuries account for approximately one in eight deaths among males and one in 14 deaths among females (51). Motor vehicle injuries alone constitute the ninth leading cause of disease burden as measured by the number of associated disability-adjusted life years (25). By the year 2020, motor vehicle injuries are projected to increase in rank to third. (ABSTRACT TRUNCATED) [ABSTRACT FROM AUTHOR]