Firearm-related injuries pose a serious public health problem in the United States and are increasingly the focus of public health concern. Despite the magnitude of this problem, ongoing and systematic collection of data on firearm-related injuries to help guide research and policy development has been lacking. The further development of firearm-related injury surveillance systems can provide an objective source of information for policy. Beginning in the mid-1980s, the Centers for Disease Control and Prevention's National Center for Injury Prevention and Control began to support the development of firearm-related injury surveillance systems by augmenting existing national- and state-level data collection systems and establishing cooperative agreements with state and local health departments to identify optimal firearm-related 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-related injury surveillance systems provides the clearest potential for linking basic information on firearm-related injuries to action, given the critical role that states have in both public health surveillance and regulation of firearms. 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 the identification of efficient techniques for linking health and criminal justice data sources are among the key challenges we face as we try to build a more uniform system for monitoring firearm-related injuries in the United States.