he Probate Court of Sonoma County officially existed from 1 May 1851 through 31 December 1879 and handled all matters pertaining to the disposition of deceased persons' estates and the guardianship of minors and insane or incompetent persons. Knowing the probate case file number researchers can locate the probate case file containing all of the papers filed in the case housed at the Sonoma County Superior Court. To fully understand how a probate case unfolded over time, however, in addition to the filed documents in the probate case file both the fee book and registers and minute books of the court which handled the probate case need to be consulted. Unfortunately, for most courts, these bound volumes are usually unindexed, requiring tedious page-by-page searches for information about each probate case. This publication assists researchers by providing an index to both the fee book and registers and minute books of the Probate Court of Sonoma County, 1847-1879. It includes Sonoma County probate case file numbers 1 through 1056 and comprises over 1,400 individual entries. This index to the records of the Probate Court of Sonoma County is presented in a five-column tabular form, which includes the headings: Name (person or persons associated with each case, arranged alphabetically by surname), File # (probate case file number), Type (type of probate case), Fee Book & Register (volume and page number), and Minute Book (volume and page number). Researchers should use this index to locate the appropriate entries in the Sonoma County Probate Court fee book and registers and minute books to reconstruct the proceedings of the probate case and examine each and every document in an individual's probate case file.