The objective of this study was to describe where students from lower-income, ethnically diverse communities obtain the sugar-sweetened beverages (SSBs) they drink during school lunchtime and to examine whether students who purchase beverages while traveling to and from school are more likely to drink SSBs during lunchtime. This cross-sectional study used survey data from 597 students in 12 middle schools in the San Francisco Bay Area who participated in a larger school-based intervention promoting water access and intake. Students answered questions about what beverages they consumed during lunchtime, whether and from where they purchase beverages on the way to and from school, and their socio-demographic characteristics. One-fifth (20.4%) of students reported drinking an SSB during lunch. The most popular SSBs consumed were sugary fruit drinks, sports drinks, and soda. Approximately 23 percent of SSBs consumed at school were obtained during the school commute, 23 percent were obtained from a friend at school, and 34 percent were brought from home. Students buying beverages most often stopped at convenience/corner stores (71.8%), grocery stores (41.5%), and fast-food restaurants (15.9%). Students who reported buying beverages during their school commute were significantly more likely to report drinking SSBs during lunch than students who did not.