With data from the Center for Disease Control's Behavioral Risk Factor Surveillance System, we estimated the prevalence of homes with inadequate smoke detector protection from residential fires in Pennsylvania and identified the characteristics of these homes in an effort to identify useful prevention strategies for Pennsylvania and other regions with similar characteristics. Homes with inadequate smoke detector protection from residential fires were defined on three levels. Eight percent (95% CL = 6.8, 8.6) of homes lacked any installed smoke detectors, 14% (95% CL = 12.8, 15) lacked smoke detectors installed on the same floor where they slept, and 28% (95% CL = 26.6, 29.6) were found to engage in unsafe smoke detector practices. The strong predictors of unsafe smoke detector practices determined from logistic regression included black, non-Hispanic homes (OR = 1.53), homes with annual household income of less than +20,000 (OR = 1.29), and those with no children younger than 5 years old (OR = 1.55). These findings should assist policy makers in planning residential fire prevention programs for Pennsylvania, which has yet to meet the Healthy People 2000 objective regarding fire prevention.