In June 2006, the Advisory Committee on Immunization Practices (ACIP) expanded its 2004 recommendation for routine influenza vaccination of children aged 6-23 months to include children aged 24-59 months. The 2006 ACIP recommendations also reemphasized that previously unvaccinated children aged <9 years should receive 2 doses of influenza vaccine administered at least 1 month apart to be fully vaccinated. In 2007, using data from six immunization information system (IIS) sentinel sites, CDC conducted the first assessment of influenza vaccination coverage among children aged 6-59 months during the 2006-07 influenza season. The findings demonstrated that, at all six sites, <30% of children aged 6-23 months and <20% of children aged 24-59 months were fully vaccinated. Vaccination coverage data from national and state surveys for an influenza season generally are not available until the next influenza season. Rapid assessment of influenza vaccination coverage can help direct activities of state and local public health agencies aimed at increasing the number of children fully vaccinated against influenza.