Background: School district wellness policies designed to reduce obesity and promote student health and well-being often lack specific requirements or any mandate that schools comply with the policy. Researchers, educators, and policymakers have called for states to take an active role in shaping district policies. The objective of this study was to determine if states with strong school-based nutrition and physical activity (PA)-related policies have stronger district wellness policies, and explore the direction of policy diffusion between states and districts. Methods: State policies and nationally representative samples of district policies for the 2006-2007 and 2008-2009 school years were obtained across 5 domains--competitive foods, school meals, nutrition education, physical education (PE), and PA--and were classified as "strong" or "weak," based on policy language, in each grade level (elementary, middle, high). Linear models estimated the cross-sectional and longitudinal associations between state and district policies. Results: In 2006-2007 and 2008-2009, district elementary school competitive food policies were stronger in states with strong policies. For policies governing competitive foods in high schools and school meals at all grade levels, mean district policy strength increased from 2006-2007 to 2008-2009 in states with strong 2006-2007 policies. States that strengthened their PE policies from 2006-2007 to 2008-2009 saw an increase in mean district PE policy strength. Across all domains, states that had weak 2006-2007 policies and made no changes saw little increase in district policy strength. Conclusion: District competitive food, school meal, and PE policies are stronger in states that have developed strong policies in these domains. (Contains 4 tables and 1 figure.)