Trinity traces its origins to the Rev. John Leonard Ver Mehr who immigrated to America from Belgium in 1843 and eventually settled in San Francisco.   While in San Francisco he was summoned to Baptize three girls in Sonoma.  

During a trip to Sonoma, Ver Mehr accepted an invitation to call upon Mariano Vallejo at his home overlooking the plaza.   Impressed by Ver Mehr’s credentials, Vallejo invited him to move to the valley and open a school for girls toward the end of August 1853.

On September 1, 1853, Ver Mehr opened St. Mary’s Hall which marked the beginning of Episcopal worship in the Sonoma Valley.   Ver Mehr, an ordained Episcopal priest, regarded St. Mary’s school for girls as an expression of his ministry.    

The seeds of faith planted in Sonoma by the Rev. John Ver Mehr slowly took root. He eventually left Sonoma after which Episcopal services were conducted irregularly by various clergy from surrounding parishes and communities for the next few decades. In 1911 Rev. Thomas Parker Boyd, rector at Ascension, Vallejo, began conducting regular midweek services in Sonoma.   On June 1, 1911, Boyd became the official priest-in-charge at Sonoma.

The Bishop of the Diocese of Northern California granted the town of Sonoma petition for mission status on January 21, 1912. At first, services were conducted in a large storeroom. Eventually Trinity occupied its first permanent home during mid-Lent, 1912. This building still stands on the northeast corner of East Napa and Second Street East.  

A series of fifteen priests served Trinity during the early decades of the twentieth century.   Two priests in particular provided the greatest impact on Trinity’s modern development. The Rev. Dr. Harold St. George Buttrum who remained at Trinity for eleven years, from 1945 to 1956. Under his leadership, Trinity became a full-fledged parish in 1951.  

The priest with the longest tenure in the history of Trinity was the Rev. Martin Knutsen. He arrived in Sonoma in 1959 and remained as rector for twenty-seven years. His most notable accomplishment is the design and construction in 1962 of the present church buildings and grounds.