The WHO Guidelines on risk reduction of cognitive decline and dementia provide evidence-based recommendations on lifestyle behaviours and interventions to delay or prevent cognitive decline and dementia. These WHO Guidelines are an important tool for health care providers as well as governments, policy-makers and other stakeholders to strengthen their response to the dementia challenge. Executive Summary available in Arabic, Chinese, French, Russian and Spanish at: https://www.who.int/mental_health/neurology/dementia/guidelines_risk_reduction/en/