'Growing-up milks' (GUMs)-breast-milk substitutes targeted for young children (aged 12-36 months)-are commonly consumed in Indonesia. The World Health Assembly has stated that GUMs are not necessary for proper growth and development, and recently, the American Academy of Pediatrics declared that such products are not recommended for young children due to their common use of sweeteners. To contribute to the evidence base on the composition of GUMs and their appropriateness for young child diets, this cross-sectional study documented the declared sugar content and presence of nutrient content claims of 99 GUMs newly launched in Indonesia between January 2017 and May 2019. Sugar content was evaluated against the draft 2018 Codex Alimentarius Standard for Follow-Up Formula guidance on sugar content and the United Kingdom Food Standard Agency's front-of-pack (UK FSA FOP) colour coding system for sugar. Almost all (97%) GUMs contained one or more added sugars. None of the products were fully compliant with all three sugar content recommendations in the draft Codex standard. Seventy-one per cent of GUMs were determined to have high sugar content according to the UK FSA FOP system. Nutrient content claims were found on 97% of GUMs. Median total sugar content was 7.3 g per 100 ml, similar to sugar content levels in sugar-sweetened beverages. Many GUMs available in Indonesia claim to offer nutritional benefits; however, the current levels of sugar content in GUMs are a serious concern and are inappropriate for inclusion in the diets of young children.