Purpose: To examine lunch sources during the school week among students and the associations with fruits and vegetable (F&V) and sugar-sweetened beverage (SSB) consumption. Methods: Students (n = 23 680) from 43 Ontario, Canada, secondary schools completed a health behaviour survey in the Year 1 COMPASS study. Analysis used generalized linear mixed effects models. Results: The most frequently reported lunch source was home (2.9 days per school week), then the school cafeteria (1.1) and fast-food places or restaurants (FFRs) (0.9). Eating a home lunch was associated with having less spending money, white ethnicity, and females; whereas cafeteria lunch was associated with more spending money, lower school grade, and females. A FFR lunch was associated with males, more spending money, and higher physical activity. Greater frequency of a home lunch was associated with greater F&V consumption. Greater frequency of a FFR lunch was associated with more frequent SSB consumption. Cafeteria lunches were associated with increases in both SSB and F&V. Conclusions: Eating a lunch obtained from outside of the home is a regular behaviour among students. Sources of school-week lunches may have an important influence on dietary intake among youth. These findings reinforce the need for strategies to promote healthier lunch sources and healthier food options.