San Anselmo School, located on a parcel bounded by Ross, Sunnyside, Woodland and Kensington Avenues, was originally constructed in 1898. As the school-age population grew, a second story was added to the redwood schoolhouse. With the opening of the Lansdale School in 1908, the school was renamed San Anselmo Main School and was known simply as Main School.
By 1920, Main School was overcrowded and bids were solicited for a new school building. Many longtime San Anselmo residents fondly remember the handsome red brick school that replaced the wooden schoolhouse. Completed in 1922, the new school had eight classrooms, one for each grade, with a kindergarten room upstairs. The building was arranged in a U-shape with covered walkways around a courtyard. The school fronted on Kensington which then ran through to Woodland Avenue.
A strong 6.4 earthquake in Long Beach in 1933 destroyed 70 schools and caused severe structural damage to many more. As a result, the California State Legislature enacted the Field Act one month after the quake. Under the provisions of the act, earthquake-resistant design and construction were mandated for public schools.
In April 1946, the district board decided to abandon Main School after receiving an engineering report from the State School Department which found the school to have faulty brick construction and a weaken roof support and unable to withstand an earthquake. Ironically, demolition of the brick building was slow and difficult, and dynamite was ultimately needed to bring down the structure. Students finished the year at other schools in the district.
Using prefabricated materials, a new school of modern design (single story) and better site utilization was constructed over the summer months and opened to 200 students in September only a couple of weeks late.
Wade Thomas, who had been principal of Main School and then superintendent of the school district since 1923, died unexpectedly before the school was completed. Main School was renamed in his honor.
In the early 1960s, the school district was able to acquire the property directly across Kensington. A house on the property was torn down and the road closed off to expand the school. Wade Thomas Elementary School received major upgrades after the passage of a bond measure in 1998. During 2015, the school will receive additional upgrades after voters passed another bond measure in November 2010.