Abstract This research has investigated UK food supply networks to identify the dominant causes of food waste. The aim was to develop our understanding of environmental management across multi-tier networks, with specific reference to food waste. The supply networks of 15 food commodities were investigated following a multiple case study design. A total of 101 semi-structured interviews were conducted including retailers (11), wholesalers (2), fruit and vegetable suppliers (41), and cutting plants/abattoirs (47). Waste arising across each of the 15 networks was quantified and the dominant causes of waste were identified, leading to a series of propositions to explain the management practices that trigger waste in food networks. These propositions relate to transparency of demand information, quality management, process controls, shelf-life management and packaging design, and provide insights into the actions required to mitigate the environmental impact of food production. Although the research was restricted to 15 food commodities in the UK, the findings and methods can help to motivate further research in other countries and sectors. The research is unique in terms of the scale of the data collection effort (number of commodities and interviews) and in its scope (multi-tier networks). Given the social, economic and environmental implications of food production and consumption the findings are relevant to a wide range of stakeholders in the sector.