Why and when do opposition parties in sub-Saharan Africa win the electoral support of the urban poor in the continent's major cities? This question is particularly relevant given that the strength of opposition parties is often a key indicator of democratic consolidation. In Africa, democratization has been accompanied by an explosion in urban population growth and poverty. My dissertation addresses the impact of the urban poor on the region's democratic landscape through quantitative analyses at the pan-African level and sub-national field work in key cities in Senegal and Zambia. While these are amongst the region's most urbanized democracies, the main opposition party in each country has exhibited disparate success in appealing to the urban poor. My research questions common claims in comparative and Africanist scholarship that the urban poor are entirely quiescent and that voting patterns purely reflect assessments of economic performance or an ethnic calculus. Rather, I hypothesize that understanding opposition party victories in African cities requires examining the structure of linkages between the urban poor and the existing ruling party. Where there is an organization representing the interests of a majority of the urban poor, a de-facto broker exists to channel this sector's demands to the ruling party while simultaneously providing the latter with a targeted constituency to whom clientelist benefits can be narrowly distributed in exchange for votes. Where multiple organizations represent the urban poor without a unified voice, a window of opportunity exists for political entrepreneurs and their opposition parties to emerge with a platform oriented to programmatic issues that win over a broader segment of the urban poor during elections. By studying a sector that has received scant attention in African politics and focusing on cities as a unit of analysis, this research helps refine existing understandings of democratic politics in Africa.