Objective: This report provides an overview and assessment of the School Dismissal Monitoring System (SDMS) that was developed by the Centers for Disease Control and Prevention (CDC) and the US Department of Education (ED) to monitor influenza-like illness (ILI)-related school dismissals during the 2009-2010 school year in the United States.

Methods: SDMS was developed with considerable consultation with CDC's and ED's partners. Further, each state appointed a single school dismissal monitoring contact, even if that state also had its own school-dismissal monitoring system in place. The SDMS received data from three sources: (1) direct reports submitted through CDC's Web site, (2) state monitoring systems, and (3) media scans and online searches. All cases identified through any of the three data sources were verified.

Results: Between August 3, 2009, and December 18, 2009, a total of 812 dismissal events (ie, a single school dismissal or dismissal of all schools in a district) were reported in the United States. These dismissal events had an impact on 1947 schools, approximately 623 616 students, and 40 521 teachers.

Conclusions: The SDMS yielded real-time, national summary data that were used widely throughout the US government for situational awareness to assess the impact of CDC guidance and community mitigation efforts and to inform the development of guidance, resources, and tools for schools.