This report collects statistics from a variety of sources on casualties sustained during Operation Enduring Freedom (OEF), which began on October 7, 2001, and is ongoing. OEF actions take place primarily in Afghanistan; however, OEF casualties also includes American casualties in Pakistan, Uzbekistan, Guantanamo Bay (Cuba), Djibouti, Eritrea, Ethiopia, Jordan, Kenya, Kyrgyzstan, the Philippines, Seychelles, Sudan, Tajikistan, Turkey, and Yemen. Casualty data of U.S. military forces are compiled by the U.S. Department of Defense (DOD), as tallied from the agency's press releases. Also included are statistics on those wounded but not killed. Statistics may be revised as circumstances are investigated and as records are processed through the U.S. military's casualty system. More frequent updates are available at DOD's website at http://www.defenselink.mil/news/ under "Casualty Update." A detailed casualty summary of U.S. military forces that includes data on deaths by cause, as well as statistics on soldiers wounded in action, is available at the following DOD website: http://siadapp.dmdc.osd.mil/personnel/CASUALTY/castop.htm. NATO's International Security Assistance Force (ISAF) does not post casualty statistics of the military forces of partner countries on the ISAF website at http://www.isaf.nato.int/. ISAF press releases state that it is ISAF policy to defer to the relevant national authorities to provide notice of any fatality. For this reason, this report uses fatality data of coalition forces as compiled by CNN.com and posted online at http://www.cnn.com/SPECIALS/2004/oef.casualties/index.html. The United Nations Assistance Mission to Afghanistan (UNAMA) reports casualty data of Afghan civilians semiannually, and the U.S. Department of Defense occasionally includes civilian casualty figures within its reports on Afghanistan. From July 2009 through April 2010, the Special Inspector General for Afghanistan Reconstruction (SIGAR) included statistics of casualties of members of the Afghan National Army and Afghan National Police in its quarterly reports to Congress. SIGAR has ceased this practice, and there is no other published compilation of these statistics. This report now derives casualty figures of Afghan soldiers and police from the press accounts of the Reuters "Factbox: Security Developments in Afghanistan" series and the Pajhwok Afghan News agency. Both services attribute their reported information to officials of the NATO-led ISAF or local Afghan officials. Pajhwok Afghan News frequently concludes its accounts with statements from representatives of the Taliban, however, these figures are not included in this report. Because the estimates of Afghan casualties contained in this report are based on varying time periods and have been created using different methodologies, readers should exercise caution when using them and should look to them as guideposts rather than as statements of fact. This report will be updated as needed.