Child adoption is common in Papua New Guinea (PNG), but little is known about current practices. This study describes the adoption and feeding practices among children up to 3 years of age, identified by both community-based and health facility recruitment in the Southern Highlands of PNG over a 6-month period in 2017. 85 adopted children were identified: 61 (72%) had been customarily or informally adopted and 24 babies (28%) had been sold for cash. Most (93%) were adopted at less than 1 year of age, and twothirds in the neonatal period. 73 mothers (86%) had poor knowledge of the adoption laws and processes, and 56 (66%) had poor knowledge of infant feeding practices. 8% had moderate and 9% had severe malnutrition. The common reasons for adoption were: family breakdown because of divorce, separation or the practice of polygamy; mothers who had too many children or wanted to adopt children; teenage pregnancies; and de facto relationships. 56 of the adopted children were weaned before 6 months of age, and 23 before 4 months of age, most onto a diet consisting of a limited range of fruits and vegetables. Ensuring the rights of adopted children to legal protection, optimal nutrition, care and education is essential. Knowledge of and adherence to customary adoption laws, involvement of social welfare, and infant and young child feeding practices all need to be strengthened in communities, especially in the rural areas.