The years between the American Revolution and the Civil War witnessed the prevalence of public disorder and social violence, especially in the expanding American West. In many instances, crowds took the law into their own hands and dealt summary vengeance on suspected criminals. This study delves into the political and legal climate of San Francisco in the 1850s to examine perhaps the most famous episodes of vigilantism in antebellum America; the San Francisco Vigilante Committees of 1851 and 1856. Through a careful contextualization and comparison of these committees, the thesis argues that the leaders of the respective committees believed that extralegal traditions seemed to be the best solution for securing law and order in the short run and for establishing a solid foundation for civic development. The thesis concludes with an examination of how future generations viewed these committees and their actions