During emergencies, firefighters may face challenges such as inappropriate victim responses, poor communication, and lack of needed information. Here we describe the multistep development of a questionnaire for firefighters to identify emergency-related human factors that may impair their professional performance and interfere with procedures during threatening events and evacuations. The resulting self-report questionnaire, titled the Behavior Security Culture–First Responder, comprises a battery of scales plus single questions designed for international use. We report the psychometric properties of the battery of scales and their application across 8 countries: Germany, UK, Spain, Sweden, Poland, Czech Republic, Turkey, and Italy. Exploratory factor analysis and multigroup confirmatory factor analysis were conducted with a total sample of 3,011 firefighters (97% male). Exploratory factor analysis revealed 6 unidimensional scales assessing various aspects of victim behavior, communication with others, and information availability and reliability. Multigroup confirmatory factor analyses, with the 8 countries inserted as groups, confirmed configural and metric invariance, but not scalar invariance. Internal consistency estimates of the 6 scales ranged from α = .77 to .80. Divergent validity was established for all scales in all national samples. The collected data and the questionnaire may be used for developing training programs and to aid in directing resources efficiently.