This implementation guidance supports governments and implementing organizations in adapting and adopting recommendations and good practice statements from the 2023 WHO guideline on the prevention and management of wasting and nutritional oedema (acute malnutrition) in infants and children under 5 years when updating national guidance. It incorporates standing WHO normative guidance and replaces previous operational guidance on the management of severe malnutrition. The document addresses identification, assessment, referral and nutritional, medical and psychosocial management in inpatient, outpatient and community settings for children aged 6–59 months with moderate or severe acute malnutrition and for infants less than 6 months of age at risk of poor growth and development, with or without severe acute malnutrition.