The aim was to describe milk feeding patterns and first weaning foods during the first year of life in a large prospective birth cohort of infants with increased genetic risk for Type 1 diabetes (T1D) recruited in 4 different countries: the United States, Finland, Germany, and Sweden. All enrolled children with dietary information (n = 8,673) were included in the analyses; 1,307 (15%) children who dropped out before the first birthday were excluded from some analyses. Supplementary milk feeding in the first 3 days of life was common in all the four countries, although the type of the supplementary milk differed by country and by maternal T1D. Donated human milk was commonly used only in Finland. In all the countries, the most common first supplementary food was cow's milk-based infant formula, especially among offspring of mothers with T1D. The use of specific types of infant formulas differed notably by country: Extensively hydrolysed formulas were most used in Finland, partially hydrolysed ones in the United States and in Germany, and soy formulas only in the United States. Infant formulas commonly included probiotics, prebiotics, and starches. During the first year of life, most of the infants received conventional cow's milk. Overall, milk feeding during the first 3 days of life and thereafter until the first birthday differed markedly by maternal T1D status and across countries. These descriptive data may be useful in understanding early infant feeding practices and in planning potential interventions, which affect infant feeding.