Background Firefighter safety is a top priority in wildland fire response and management. Existing explanations emphasise how land management agency initiatives to change organisational culture, usually inspired by fatality incidents, contribute to changes both in formal safety policies and informal safety practices. Aims This paper identifies external factors that lead to changes in wildland firefighter safety policies and practices. Methods This paper uses qualitative data from a long-term ethnographic research project. Data include detailed fieldnotes, semi-structured interviews, and agency documents, which were systematically coded and thematically analysed. Key results In addition to the triggering effects of fatality incidents and agency initiatives to change organisational culture, external factors also directly impact the development of firefighter safety policies and practices. These include sociodemographic, material, political, and social-environmental factors. Conclusions Identifying and understanding the influence of multi-scalar external factors on firefighter safety is essential to improving safety outcomes and reducing firefighters’ exposure to hazards. Implications Attention to and recognition of external factors is valuable for fire managers and practitioners, whose work is influenced and constrained by meso- and macro-level factors. The framework presented in this paper would be useful in understanding other important aspects of wildland fire management.