This study investigates young children's theorising about families and their differential access to food from a perspective of wealth and poverty. Fifty-two children, aged 6-7 years, attending a Western Australian school were invited to share their perspectives on this global issue. The single case study method utilised three children's focus groups to gather a range of perspectives from the children. Photographs of full and empty refrigerators were used elaborate a story told to the children about two families with significantly different amounts of food in their refrigerator at home. The study demonstrates that researchers and educators may fruitfully consider social sustainability with young children whose insights into these issues provide evidence of their clearly formed perspectives on complex global issues. Conversations about global "wicked problems" enable children to express their point of view on economic and social as well as environmental issues. The findings indicate that the young children in this study hold clear and sophisticated opinions regarding fairness, poverty, the relationship between paid work and money, food security and social justice. They also had an optimistic outlook on how to address inequality. Significant insights into children's theorising around social sustainability are presented in four themes.