Alameda County Sheriff's Office

The Alameda County Sheriff's Office (ACSO) is a law enforcement agency serving Alameda County, California. ACSO is accredited through the Commission on Accreditation for Law Enforcement Agencies (CALEA), the American Correctional Association (ACA), National Commission on Correctional Health Care (NCCHC) and the California Medical Association (CMA).

As of 2008, the ACSO has approximately 1500 positions, over 600 of which are sworn peace officers.

The Alameda County Sheriff's Office is charged with:

• Providing security to the consolidated superior courts
• Operating the coroner's bureau
• Operating a full-service crime laboratory
• Operating a county jail and detention center
• Conducting a basic academy pursuant to Police Officer Standards and Training (POST) requirements
• Performing civil processes
• Operating the county office of emergency services
• Providing fish and game enforcement
• Operating a marine patrol unit in the San Francisco Bay waters
• Providing patrol and investigative services to the unincorporated areas of Alameda County
• Pursuant to contractual agreements, providing patrol and investigative services to the city of Dublin, Peralta Community College District, Oakland-Alameda County Coliseum complex, Oakland International Airport, Highland County Hospital, social services, and to the Alameda-Contra Costa Transit District

The Sheriff-Coroner is an elected position currently filled by Yesenia Sanchez. The previous sheriff, Gregory J. Ahern, served from 2007 to 2023.