The Preston School of Industry, also known as Preston Castle, was a reform school located in Ione, California, in Amador County. It was proposed by, and ultimately named after, state senator Edward Myers Preston. The cornerstone was laid in December 1890, and the institution was opened in June 1894 when seven wards, were transferred there from San Quentin State Prison. It is considered one of the oldest and best-known reform schools in the United States.
The original building, known colloquially as "Preston Castle", is the most significant example of Romanesque Revival architecture in the Mother Lode. This building was vacated in 1960, shortly after new buildings had been constructed to replace it, and has since been named a California Historical Landmark, and listed on the National Register of Historic Places.
In 1999, the institution's official name, applied to the newer 1960 buildings, was changed to the "Preston Youth Correctional Facility".
In 2010, the California Department of Corrections and Rehabilitation announced that the facility was to close, and a closing ceremony was held on June 2, 2011.