In the 1850s and 1860s, St. Mark's also a center for African American political activity. The church hosted three of the four California Colored Citizen's Conventions. The conventions were held, in part, to highlight the achievements of African Americans in the state but also to express their grievances. Although they lived in a state which was, theoretically, free, African Americans could not testify in court and African American men could not vote. When California became a state, some legislators wanted to prohibit African Americans from entering the state.
Many years later in the 1920s, the church's integral role in Sacramento's African American community was illustrated when W.E.B. DuBois visited the city and insisted on speaking at the church. The current building was constructed in 1951. The site of the original church building at 715 Seventh Street, is now used for parking, but a historical marker identifies it as the site of the original structure.