A BATF trace typically reveals the gun’s history from its manufacture to its sale by a licensed retail firearms dealer. BATF traces occasionally have been a useful tool for investigating individual crimes. Some persons have also tried to use BATF trace data in recent years to study gun violence and evaluate firearms policies. The BATF traces have severe limitations as useful data for criminological analysis. These limits include the relatively small number of crime guns that BATF traces, BATF’s rules about what guns it will not even attempt to trace, and the limited information supplied by gun traces. The analysis concludes that BATF trace figures are not a sound foundation for criminological research and that routinely gathering additional information on BATF forms and providing better guidance to local law enforcement would help make BATF trace data a useful data source for such research. Notes and 52 references (Author abstract modified)