This collection of records are contained in a single volume register of prisoners received in and discharged from San Luis Obispo County Jail, July 1, 1912 -September 30, 1913. The register provides the date on which a prisoner was received, his name and crime, the arresting officer's name, the name of the sentencing judge, and the date and by what authority the prisoner is discharged. In some cases, the number of days spent in jail and jail fines paid are also listed. There is an index to the sixty-two pages of prisoners in the register.

San Luis Obispo county was a "late-blooming" political sub-division. Despite the presence of a Spanish mission on the site of the county seat, the city of San Luis Obispo was not incorporated until 1876 and the railroad did not reach the city until 1894. By 1912 San Luis had a population of 5,000 people.

Collection is open for research.