The UCR data cannot reveal the number of murders nor the number of willful criminal homicides, the circumstances of the homicide, or the victim-offender relationship. Further, they often may not be able to provide reliable information on weapons use. The only major improvement in the data that will result from proposed reforms will be an attempt to identify self-defense killings. Within the broad confines generally understood by criminologists, the UCR data are useful, but caution must be exercised in using the data for analysis. 42 references.