As temperatures rise, so do risks to workers. Heat Stress at Work examines how extreme heat affects workers across sectors, particularly those in high-exposure roles or due to existing inequalities and vulnerabilities. It analyses workplace practices, regulatory settings and economic pressures that influence risk, and highlights consequences for health, productivity and business continuity. This report identifies practical opportunities to strengthen worker protection and embed heat risk management within occupational health and safety systems. This report forms part of the first Post-Event Review Capability (PERC) on extreme heat, with the findings unfolding across three interconnected reports: Understanding Extreme Heat and Entry Points for Action and Strengthening Resilience to Extreme Heat: An Adelaide Case Study. Together, they build a layered picture of how extreme heat risk is shaped, experienced and addressed.