Purpose: Paramedics' work environment is constantly changing and unpredictable. Controlling environmental risks is difficult for the HR department and requires support of external systems such as unions and policymakers. Acknowledging environmental complexity, and the interaction of external systems, this study examines how the HRM system manages and responds to violence against paramedics. Design/methodology/approach: Data were collected from three Australian state ambulance services. Detailed accounts from 72 semi-structured interviews are supplemented by 1,216 phone surveys demonstrating the prevalence of assault. Findings: Reporting very high levels of assault against paramedics from the survey data, the authors discuss situational risk factors identified by interviewees in the immediate physical environment and broader social context. The authors detail HRM practices adopted by each case and identify how gaps in the HRM system are addressed by other external, industry-level and state/federal-level systems in a multi-layer response to assault against paramedics. Practical implications: Identification of individual and situational risk factors and consequences for paramedics enables more targeted prevention, intervention and response. Young and less experienced paramedics are perceived to be at greater risk of assault. Importance of HRM practices particularly de-escalation training is highlighted. Gaps in HRM system require external input, particularly via law enforcement and public education. Originality/value: This study adopts a holistic and contextualised perspective of HRM to improve understanding of violence against paramedics at work. Combining open systems and multi-stakeholder approaches, the authors adapt Beer et al.'s (1984) seminal Harvard Model of HRM. The authors propose a conceptual map which illustrates relationships between situational risks, key systems, HRM practices and outcomes.