Mental disorders among children are described as "serious deviations from expected cognitive, social, and emotional development" (US Department of Health and Human Services Health Resources and Services Administration, Maternal and Child Health Bureau. Mental health: A report of the Surgeon General. Rockville, MD: US Department of Health and Human Services, Substance Abuse and Mental Health Services Administration, Center for Mental Health Services, and National Institutes of Health, National Institute of Mental Health; 1999). These disorders are an important public health issue in the United States because of their prevalence, early onset, and impact on the child, family, and community, with an estimated total annual cost of $247 billion. A total of 13%-20% of children living in the United States experience a mental disorder in a given year, and surveillance during 1994-2011 has shown the prevalence of these conditions to be increasing. Suicide, which can result from the interaction of mental disorders and other factors, was the second leading cause of death among children aged 12-17 years in 2010. Surveillance efforts are critical for documenting the impact of mental disorders and for informing policy, prevention, and resource allocation. This report summarizes information about ongoing federal surveillance systems that can provide estimates of the prevalence of mental disorders and indicators of mental health among children living in the United States, presents estimates of childhood mental disorders and indicators from these systems during 2005-2011, explains limitations, and identifies gaps in information while presenting strategies to bridge those gaps.