Bonds guaranteeing the faithful performance of the duties of their offices have been required of Californian public officials since the formation of the state. One of the first statutes passed by the California legislature was "An Act Concerning the Official Bonds of Officers," which set out the basic law governing bonds of both state and county public officials. Before taking office, a public official, known as the "principal" of the bond, was required to pledge a certain amount of money, $100 to $100,000 depending on the office, which would be forfeited to the State of California should the public official not faithfully perform the duties of his or her office. Two or more other persons, the "sureties" of the bond, usually the principal's friends or family, were required to pledge at least an equal amount. After approval by the County Court Judge (later the Superior Court Judge or Judges), the bonds were filed and recorded in the office of the County Clerk or Recorder. The information extracted from each public official bond for this index includes the bond principal's name, the sureties' names, the amount and date of the bond, the office to which the public official was appointed or elected, any relevant information contained in the text of the bond, and the book and page(s) in which the bond was recorded. Information within the appropriate books of three series of volumes of Sonoma County recorded bonds was also extracted, capturing public official bonds for which no originals were found in the Sonoma County Archives. Over 2,300 bonds of Sonoma County public officials dated from 1850 through 1892 are indexed in this publication.