OBJECTIVE: To determine the household prevalence of firearms in Pennsylvania, and describe the storage practices for these weapons. DESIGN: A statewide telephone survey of 3,620 Pennsylvania adults selected from households by random digit dialing in 1994. MAIN OUTCOME MEASURES: Firearm ownership and storage practices were computed by household characteristics using logistic regression. RESULTS: The prevalence of firearm ownership was 37% (95% confidence interval = 35.4 to 38.6). Ownership of firearms was significantly higher for white residents, households with annual income of $20,000 or more, those in rural counties, and those with children and adolescents. Of the households with firearms, 23% contained a single firearm, the majority of which were handguns (40%) or rifles (40%); 76% had two or more firearms, with 57% reporting one handgun or more and 83% reporting one rifle or more. Storage of firearms in 72% of households involved two or more of these barriers: (1) taken apart; (2) trigger lock applied; (3) kept in a locked place; (4) unloaded; (5) no other ammunition; (6) locked ammunition; 6% stored at least one of their firearms with none of these barriers. The strongest predictor of storing a firearm with fewer than two protective barriers was households with no children or adolescents. CONCLUSIONS: Firearms are present in a large number of Pennsylvania homes. Many of these homes also contain children. To reduce the potential risks of firearms, optimal methods of storage of firearms in the home need to be determined.