Background Recent federal proposals in Canada have called for changes in the delivery and funding of school lunches. Yet little evidence has documented the nutritional quality of meals eaten by school children, which is needed to inform school lunch reforms. Objectives To assess the dietary contributions of lunch foods to daily food and nutrient intakes on school days and compare dietary intakes across eating locations (school, home, and off campus). Design Cross-sectional analyses of school day data from the 2015 Canadian Community Health Survey-Nutrition. Participants/setting Children aged 6 to 17 years who completed a 24-hour dietary recall falling on a school day in 2015 (n¼2,540). Main outcome measures Mean percent of daily intakes of energy, food groups, and nutrients contributed by foods reported at lunch and energy-adjusted intakes of nutrients and food groups consumed during the lunch meal. Statistical analyses Descriptive statistics were used to assess the percent of daily energy, nutrients, and food groups contributed by lunch foods. Multivariable linear regression models examined differences in dietary outcomes across eating locations for the full sample and stratified by age group, with separate models for children aged 6 to 13 and 14 to 17 years. Results On average, foods reported at lunch provided w26% of daily calories on school days. Relative to energy, lunch foods provided lower contributions of dark green and orange vegetables, whole fruit, fruit juice, whole grains, milk and alternatives, fluid milk; minimally nutritious foods including sugar-sweetened beverages; and several related nutrients including total sugars; vitamins A, D, B-6, and B-12; riboflavin; and calcium. Yet, lunch foods provided proportionally higher contributions of grain products, nonewhole grains, meat and alternatives, and sodium. Children aged 14 to 17 years who ate lunch at school reported higher intakes of total vegetables and fruit, whole fruit, whole grains, fiber, vitamin C, and magnesium but reported fewer calories from sugar-sweetened beverages compared with their peers who ate lunch off campus. Conclusions Relative to its contribution to energy, lunch on school days contributed to proportionally lower intakes of many healthful foods such as dark green and orange vegetables, whole fruit, whole grains, and fluid milk but also proportionally lower intakes of other high-fat and high-sugar foods including sugar-sweetened beverages. This study adds to the growing body of evidence on dietary concerns during school time for Canadian children and highlights particular nutritional challenges for adolescents consuming lunch off campus.