As the Japanese population of California increased, so did anti-Japanese sentiment and efforts to contain the perceived threat posed that population. In 1921, the Parker Bill was passed, which placed Japanese language schools under the authority of the Superintendent of Public Instruction. Instructors at the schools were required to be proficient in the English language and to have knowledge of American history. They were also required to pledge to work to make Japanese-American students good American citizens.
At the time, Walnut Grove had a Japanese population, most of which was concentrated in the neighborhood known as Japantown. Walnut Grove was known as Kawashimo, and its Japantown flourished, although most of the land and businesses in the area were owned by a few white residents. Japantown was home to a number of businesses and institutions that catered to Japanese-Americans, including a Buddhist temple.
Another institution located in Japantown was Gakuen Hall, a Japanese language school. Gakuen Hall is the only known example of a Japanese language school built by Japanese themselves in response to segregated schools.During World War II, when Japanese-Americans were interned, the building was held in trust by a local landowner until Walnut Grove's interned residents returned.
Gakuen Hall is listed on the National Register of Historic Places, as is the Walnut Grove Japanese-American Historic District.