In India, a young democratic system has undermined the legitimacy of a two-thousand-year-old social system that excluded and humiliated an entire people by treating them as untouchables. This incomplete, but irreversible change in Indian society and politics has been authored by the mobilization of some of the most marginalized citizens in the world and counts as one of the most significant achievements of Indian democracy. Dalits, the former untouchables in India, who number over 200 million, have been mobilized by social movements and political parties, but their mobilization is puzzling. Dalits’ parties perform poorly in elections in states historically home to movements demanding social equality while they do well in other states where such movements have been weak or entirely absent. For Dalits, collective action in the social sphere appears to undermine rather than bolster collective action in the electoral sphere. Mobilizing the Marginalized shows how social movements by marginalized ethnic groups—those who are stigmatized by others and disproportionately poor—undermine bloc voting to generate competition for marginalized citizens’ votes across political parties. The book presents evidence showing that a marginalized group gains more from participating in a social movement and dividing support among parties than from voting en bloc for an ethnic party.