Study aim: To determine if pupil physical activity and Body Mass Index classifications maintained or improved after a one-year professional development program involving both classroom and physical education teachers. Guskey's model of teacher change guided this study. Material and methods: Indigenous children from ten schools (N = 320) in grades 3-12 from one community participated in this year-long comprehensive school change effort. Classroom (n = 31) and physical education teachers (n = 7) participated in this study as intervention (n = 27) or comparison (n = 11) teachers. Intervention teachers participated in a year-long professional development program to increase physical activity and healthy behaviour knowledge of pupils. Results: ANOVA results for pupil physical activity (measured using pedometry) indicated that both groups of pupils (intervention and comparison) became significantly more active over time. The intervention groups' behaviour was less stable (alpha = 0.71) over time versus the comparison group (alpha = 0.86), suggesting positive behaviour changes. No significant Body Mass Index changes were found. Conclusions: Although the intervention resulted in physical activity increases for both intervention and comparison pupils at the schools, change takes time and these initial findings show progress in increasing physical activity behaviours at school in an understudied and disadvantaged population of indigenous USA youth. (Contains 1 table.)