This chapter is concerned with identifying: (i) challenges to food systems in Africa, Asia, and Latin America caused by urban development, (ii) how existing food systems respond to these challenges, and (iii) what can be done to improve their responsiveness. The chapter is based on the authors’ published research complemented by additional literature. We define ‘urban food systems’ as food systems linked to cities by material and human flows. Urbanisation poses challenges related to food and nutritional security with the co-existence of multiple forms of malnutrition (especially for women and children/adolescents), changing employment (including for women), and environmental protection. It is widely acknowledged that contemporary food systems respond differently to these challenges according to their traditional (small-scale, subsistence, informal) versus modern (large-scale, value-oriented, formal) characteristics. We go beyond this classification and propose six types of urban food system: subsistence, short relational, long relational, value-oriented small and medium enterprise (SME)-driven, value-oriented supermarket-driven, and digital. These correspond to different consumer food environments in terms of subsistence versus market orientation, access through retail markets, shops or supermarkets, diversity of food, prices and food quality attributes. Urban food supply chains differ not only in scale and technology, but also in the origin (rural, urban or imports) and perishability of food products. We stress the complementarity between short chains that supply many perishable and fresh food items (usually nutrient-dense) and long chains that involve collectors, wholesalers, retailers, storage and processing enterprises for many calorie-rich staple food commodities. More and more SMEs are upgrading their business through technologies, consumer orientation, and stakeholder coordination patterns, including food clusters and alliances.Urban food systems based on micro, small and medium enterprises (MSMEs) have proven resilient in times of crisis (including in the ongoing Covid-19 pandemic). Rather than promoting the linear development of so-called ‘traditional’ towards ‘modern’ food systems, we propose seven sets of recommendations aimed at further upgrading MSME business, improving the affordability and accessibility of food to ensure food and nutritional security while accounting for the specificities of urban contexts of low- and middle-income countries.