This research explores the social life of street food in Hanoi, Vietnam, using a conceptual framework of social sustainability. Although the economic benefits of street vending are widely recognised, little attention has previously been paid to the social aspects. Focusing specifically on the selling of street food through the lens of social sustainability, this research develops a conceptual framework from the literature. The framework comprised eight key themes: social justice, quality of life and well-being, participation, safety and security, social interactions and social networks, social inclusion, sense of place and cultural heritage and was applied empirically to the street food environment of Hanoi. The themes used in the framework were identified as the most pertinent in the literature and were grouped under three broad ideas – social justice, social relations and culture – and used to frame the thesis. The application of the social sustainability framework revealed important details about the social life and social function of the street food environment. It highlighted key areas where street food in Hanoi can be shown to contribute to the principles of social sustainability, such as regarding social relations, cultural heritage and sense of place. It also drew attention to areas that require improvement, including some aspects of social justice, for example, participation, safety and security and food hygiene. The findings of this research suggest the challenges identified that prevent the social sustainability of street food in Hanoi, often manifested themselves through the inequalities experienced between the different types of street food vendors, specifically itinerant or migrant vendors compared to local vendors with fixed selling locations. The thesis argues that the approach adopted in the research offers a useful tool for understanding the social functions of street vending which can be applied and adapted to examine the social sustainability of street food vending in other economic and political contexts.