['To assess school-level characteristics associated with Team Nutrition (TN) program participation, and compare the availability of food items in school lunches in participating vs nonparticipating schools.', 'Cross-sectional study with a nationally representative sample of 2,489 elementary schools in the United States. A mail-back survey was used to collect school administrator-reported annual data on availability of selected healthful and unhealthful lunch items between 2006-2007 and 2009-2010. Multivariate regression analyses was used to predict the availability of food items in school lunches based on TN participation.', 'Team Nutrition participation was higher among schools in the south, in rural areas, and in states with stronger nutrition policies. Program participation was higher in schools with mostly low-income students and where a dietitian was on staff. Participating schools were more likely to offer healthful items and less likely to serve unhealthful items during lunch.'] Is elementary school participation in the United States Department of Agriculture 's Team Nutrition program associated with more healthful school lunches?