Firearms are a leading cause of death in the United States, yet the effort to understand their aggregate impact on the public's health has only just begun. There were 26,442 firearm deaths among California residents during the years 1977 through 1983. During this period firearms were the eighth leading cause of death for California as a whole, sixth for male Californians and first for black males aged 15 to 34 years and black females aged 15 to 24 years. A plurality of firearm deaths were suicides; unintentional deaths contributed only 3% of the total. Black men aged 25 to 34 years had the single highest firearm mortality rate; 80% of firearm deaths in that group were homicides. Men 75 years old and older had the highest firearm mortality rate when all races were considered together, however, and 93% of firearm deaths in that group were suicides. The discussion focuses on our current understanding of firearms as a medical and public health problem and suggests directions for future research and intervention.