This dissertation explores the environmental and legal context of political activism among southern California Indians between 1850 and 1934. Specifically, it tracks the rise of the Mission Indian Federation in the early part of the twentieth century as one example of the ways Indians reacted to the creation of federal reservations, regional water development, and the agricultural models of "civilization" the Indian Office sought to implement. Across the region, Indians turned toward the courts and the newly-formed political institutions of the reservations to carve out indigenous political power and sovereignty for themselves. They articulated a vision of Indian sovereignty under the motto "Human Rights and Home Rule," and used it to challenge the power of the federal government.