Prevalence of obesity among American Indian children is higher than the general US population. The school environment and teachers play important roles in helping students develop healthy eating habits. The aim of this prospective study was to examine teachers' classroom and school food practices and beliefs and the effect of teacher training on these practices and beliefs. Data were used from the Bright Start study, a group-randomized, school-based trial that took place on the Pine Ridge American Indian reservation (fall 2005 to spring 2008).