The national school lunch and breakfast programs provide inexpensive or free meals to more than 27 million children each day. During the 1990s, nearly 300 outbreaks of foodborne illness at the nation's schools sickened 16,000 students. The rise in the number of school outbreaks mirrors a rise in the number of outbreaks in the overall population, according to the Centers for Disease Control and Prevention (CDC). Because the CDC data include outbreaks attributable to food brought from home or other sources, GAO could not determine the extent to which food served in the school meal programs caused reported outbreaks. Data from 1998 and 1999 do show, however, that most of the outbreaks during those years were caused by foods served through the school meal program. Foods contaminated with salmonella and Norwalk-like viruses were the most common causes of outbreaks. GAO found that the Department of Agriculture has not developed security measures to protect foods served at schools from deliberate contamination. The existing food safety system is a patchwork of protections that fall short in addressing existing and emerging food safety threats.