The National School Lunch Program (NSLP) is the Nation's second-largest food and nutrition assistance program, providing billions of meals to tens of millions of children and adolescents each year. USDA, Economic Research Service (ERS) periodically reports on NSLP policies and program operations, often after major changes to the program's rules and guidelines. The last such report was published in 2008. Since then, the program has undergone major changes precipitated by the passage of the Healthy, Hunger-Free Kids Act of 2010 and the effects of the Coronavirus (COVID-19) pandemic. Changing economic conditions may have also affected program spending and participation. This report provides an overview of the NSLP, documents major program changes since 2008, and examines historical trends and participant characteristics. It also summarizes research on the financial status of school food authorities, program participation, the nutritional quality of school lunches, and the impact of the program on the diets of children and adolescents. It concludes by discussing issues facing the program and research and data needs.