Background: The Child Nutrition and WIC Reauthorization Act of 2004 (hereafter called the 2004 Reauthorization Act) was federal legislation that required school districts participating in the federally funded school meal program to develop and implement policies addressing nutrition guidelines for all foods and beverages available on school campuses by the onset of the 2006/2007 school year. Purpose: Vending machine and school store (VMSS) availability and low-nutrient, energy-dense snacks and beverages in VMSS were assessed in a statewide sample of Minnesota secondary schools before and after the 2004 Reauthorization Act was implemented in 2006/2007. Methods: The CDC School Health Profiles principal survey was collected from a representative sample of middle (n=170) and high (n=392) schools biennially from 2002 to 2010. Trends were estimated using general linear models with a logit link and linear spline modeling. Analyses were conducted in 2012. Results: Among high schools, VMSS (p=0.001) and sugar-sweetened beverages (p=0.004), high-fat salty snacks (p=0.001), and candy (p=0.001) in VMSS decreased from 2002 to 2008. In 2008, a change in slope direction from negative to positive occurred for all food practices and an increase in VMSS (p=0.014) and sugar-sweetened beverages (p=0.033) was seen. Among middle schools, VMSS (p=0.027), sugar-sweetened beverages (p=0.001), high-fat salty snacks (p=0.001), and candy (p=0.029) decreased from 2002 to 2010. Conclusions: This study supports a link between policy and sustainable decreases in some food practices but not others and a differential effect that favors middle schools over high schools. Policy-setting is a dynamic process requiring ongoing surveillance to identify shifting trends.