The further development of firearm injury surveillance systems can provide an objective source of information for policy. Since the mid-1980s, the National Center for Injury Prevention and Control has supported the development of firearm injury surveillance systems by augmenting existing national and State data collection systems and by establishing cooperative agreements with State and local health departments to identify optimum firearm injury surveillance practices. Some progress has been made in improving the capacity to undertake firearm injury surveillance at national, State, and local levels for mortality, morbidity (including disability), and risk-protective factors, but much work remains to be done. The development of State and local firearm injury surveillance systems offers the clearest potential for linking basic information on firearm injuries to action, given the critical role of States in both public health and firearm regulation. Key challenges of any effort to build a more uniform system for monitoring firearm injuries include broader application of external cause-of-injury codes, increased standardization and validation of definitions and data collection instruments, improved methods for identifying firearm characteristics and types, and identification of efficient techniques for linking health and criminal justice data sources. 41 references, 3 tables, and 1 figure