Background: The high prevalence of obesity puts children at risk for chronic diseases, increases health care costs, and threatens to reduce life expectancy. As part of the response to this epidemic, the New York City (NYC) Department of Education (DOE)--the nation's largest school district--has worked to improve the appeal and nutritional quality of school food. This article highlights some of the structural and policy changes that have improved the school food environment over the past decade, with the aim to share lessons learned and provide recommendations and resources for other districts interested in making similar modifications. Methods: This article details changes DOE has implemented over 10 years, including revised nutrition standards for school meals and competitive foods; new school food department staffing; food reformulations, substitutions, and additions; and transitions to healthier beverages. Results: NYC's revised nutrition standards and hiring of expert staff increased availability of fruits and vegetables, whole grains, and low-fat dairy and decreased sugary beverages, and foods high in saturated fats and added sugars--the major contributors to discretionary calorie intake. DOE also introduced healthier beverages: switching from high-calorie, high-fat whole milk to low-fat milk and increasing access to water. Conclusions: NYC has successfully improved the quality of its school food environment and shown that healthier food service is possible, even under budgetary constraints. Several broad factors facilitated these efforts: fostering community partnerships and inter-agency collaboration, implementing policies and initiatives that target multiple sectors for greater impact, and working to make incremental improvements each year. (Contains 2 tables and 1 figure.)