168 pages ; Food and nutrition insecurity are major threats to public health, impacting diet quality and the risk of diet-related chronic diseases. Climate change is also a major threat to public health and is expected to exacerbate both food and nutrition security. Addressing nutrition and food insecurity while also reducing the environmental impacts of the food system is an important pursuit. The food environment can influence an individual’s food and nutrition security status, and/or ability to adopt a sustainable dietary pattern. In this dissertation, mixed-methods were used to understand the food environment and its interaction with sociodemographic characteristics, as well as to understand barriers and enablers food retailers face regarding improving nutrient-dense food offerings and food sustainability practices in New York City (NYC). In Chapter 2, the relationships of community district bodega-to-supermarket ratio (BSR) with sociodemographic characteristics and select diet outcomes were explored. In Chapter 3, a scoping review was conducted to summarize existing consumer nutrition environment measurements. In Chapters 4 and 5, semi-structured interviews were conducted with food retail stakeholders to understand barriers and enablers to offering nutrient-dense foods and engaging in food sustainability practices. Results from the first study showed that higher BSR was significantly associated with poverty, increased sugary drink intake, and decreased fruit and vegetable intake. Community districts with larger Latino and white populations had significantly higher and lower BSR, respectively. The scoping review found that many consumer food environment measures exist, though few have been rigorously assessed for reliability and validity, and only two assess environmental sustainability. Qualitative interviews suggest many food retailers offer nutrient-dense foods, but some face barriers related to infrastructure or storage to offering more. Common sustainability practices include food loss waste reduction, ...