ISO 45003 gives HR and safety leaders a structured way to manage psychosocial risks — the workplace factors such as excessive workload, poor leadership, harassment, and job insecurity that affect employee mental health — by applying the same rigor to psychological hazards that traditional safety frameworks apply to physical ones. Formally titled ISO 45003:2021, it is a guidance standard, not a certification standard: it does not replace ISO 45001 but builds on it, and organizations cannot certify to it on its own, though third parties can assess alignment during an ISO 45001 audit. This guide translates the standard's principles into two practical tools: a three-part model for systematically identifying psychosocial hazards, and a phased roadmap for embedding the guidelines into an existing occupational health and safety (OHS) system.