In 2011, correctional administrators reported 6,660 allegations of sexual victimization in prisons. Of these, 605 were substantiated based on follow-up investigation. Local jail authorities reported 2,042 allegations, of which 284 were substantiated. About half (51%) involved allegations of nonconsensual sexual acts or abusive sexual contacts of inmates with other inmates, and half (49%) involved staff sexual misconduct or sexual harassment directed toward inmates. While the overall number of allegations reported by authorities in adult correctional facilities rose from an estimated 6,241 in 2005 to 8,763 in 2011, the number of substantiated incidents did not change significantly from 2005 (885) to 2011 (902). Data are from the Bureau of Justice Statistics' (BJS) Survey of Sexual Violence (SSV), which has annually collected official records on allegations and substantiated incidents of inmate-on-inmate and staff-on-inmate sexual victimization since 2004. The SSV is one of a number of BJS data collections that are conducted to meet the mandates of the Prison Rape Elimination Act of 2003 (PREA). On behalf of BJS, staff of the U.S. Census Bureau mailed survey forms to correctional administrators in the Federal Bureau of Prisons, state prison systems, public and private jails, private prisons, jails in Indian country, and facilities operated by the U.S. military and Immigration and Customs Enforcement (ICE). Administrators were given the option of mailing back a completed form or completing it on the internet. Data collection forms can be accessed on the BJS website. The administrators then completed a separate form for each substantiated incident, providing details about the victim, perpetrator, and circumstances surrounding the incident. The 2009, 2010, and 2011 surveys included all federal and state prisons, facilities operated by the U.S. military and ICE, and a representative sample of jail jurisdictions, privately operated jails and prisons, and jails holding adults in Indian country. In total, data were collected from facilities containing 1.99 million inmates in 2009, 1.98 million inmates in 2010, and 1.97 million inmates in 2011. (See Methodology for more information about the systems and facilities from which data were collected.)