Background: The availability of competitive foods in schools is a modifiable factor in efforts to prevent childhood obesity. The Alliance for a Healthier Generation launched the Healthy Schools Program in 2006 to encourage schools to create healthier food environments, including the adoption of nutritional guidelines for competitive beverages and foods. This study examines nationwide awareness and implementation of the guidelines in US public elementary schools. Methods: Data were collected from a nationally representative sample of elementary schools using mail-back surveys in 2006-2007, 2007-2008, 2008-2009, and 2009-2010. Results: From 2006-2007 to 2009-2010, awareness of the Alliance's beverage guidelines increased from 35.0% to 51.8% among school administrators (p less than 0.01); awareness of the food guidelines increased from 29.4% to 40.2% (p less than 0.01). By 2009-2010, almost one third of the schools that sold competitive beverages and foods reported having implemented or being in the process of implementing the guidelines. Implementation was higher among schools from Southern states. Schools with a majority of Black or Latino students were less likely to implement the guidelines. Conclusions: Awareness and implementation of the Alliance's beverage and food guidelines has significantly increased since the 2006-2007 school year, indicating successful diffusion of the guidelines. However, many administrators at schools who sold competitive products were not aware of the guidelines, indicating a need for continued efforts. In addition, lower implementation among schools serving minority students suggests that the Alliance's targeted efforts to provide intensive technical assistance to such schools is warranted and necessary. (Contains 5 tables.)