Firefighting is wrought with risk, as 80-100 firefighters (FFs) die on the job each year in the United States. Many of the fatalities have been analyzed by the National Institute for Occupational Safety and Health (NIOSH) to determine contributing factors. The purpose of this study is to determine variables that put FFs at risk for potentially preventable workplace mortality such as use of personal protective equipment (PPE), seat belts, and appropriate training/fitness/clearance for duty. The NIOSH FF Fatality Database reports from 2009 to 2014 were analyzed. Data including age, gender, years on the job, weather, other calls on the same shift, and department type were compared between FFs who employed PPE, seat belts, or wellness/fitness and those who did not. A second group of FFs was determined by NIOSH to have inexperience, lack of training, or inappropriate clearance for duty implicated in their fatalities. Comparisons for the second group were between those whose department used training and safety-related standard operating protocols and those who did not. In 84/176 deaths, PPE/seat belts/fitness was implicated in the fatality. Lack of PPE was more likely on clear days (P = .03) but less likely on cloudy and windy days (P < .001). These FFs dying with lack of PPE had more time on the job in a single department, 18 vs 13 years (P = .03), and more time in a volunteer department, 17 vs 8 years (P < .01). Being deployed on another call during the same shift was associated with lack of PPE-34 vs 16% of those who had not been on another call (P = .005). Lack of training, experience, or medical clearance was implicated in fatalities for 100/176 FFs. FFs who worked in departments that lacked standard operating protocols for respirator fit testing, PPE, fitness testing, rapid intervention, medical clearance, safety/distress alarms, vehicle maintenance, or incident command were statistically more likely to have lack of experience/training/clearance implicated in the fatality. Good weather during a call and more years on the job, particularly in a volunteer department, are associated with FF mortality related to unsafe practices. These factors might create an air of complacency that puts FFs at risk for safety-related omissions. Having been on a recent call may create distraction or fatigue that puts FF at risk during subsequent calls. Lack of key safety-related protocols appears to put FFs at risk of mortality, and the risk may be increasing over time. Further study and prevention efforts from multidisciplinary groups are needed to better understand and combat this problem.