This research adopts a cross-regional comparative historical and a political economy approach to democratization processes in the Global South. It explains why in Egypt (1952-2016) and Brazil (1930-2016) where calls for democratization and regime change were preceded by class struggles and an impressive wave of working-class activism, the Brazilian working class broke free from corporatism and built a broad and strong alliance with other struggling social classes while the Egyptian working class was not able to fulfill this objective. While Brazil transitioned to a democracy until 2016, Egypt experienced the rise of the military to power since 2013. These different outcomes are explained by embedding the questions of working class organizing and the absence or presence of broad inter-class alliances in the will of the authoritarian leaders to leave power or to entrench authoritarian rule, as well as the will of the military in particular to tolerate or repress opposition. The dissertation assesses this question of military tolerance of opposition or lack thereof, by looking at the institutional, foreign policy and economic interests of the military. The analysis puts the focus on the way such interests evolved under authoritarianism and the way the military was constituted and shaped by capitalism and hence by its relationship with the owners of capital and labor. The research contributes to the comparative democratization literature by pursuing a multi-disciplinary approach that combines theoretical insights from comparative politics, political economy, critical history and geography as well as the regional Latin American and Middle Eastern literature. It also expands the geographical scope of the academic conversation by examining the challenges of democratization in post-colonial societies and by incorporating cases from the Arab world that had been hitherto unexamined by the democratization and regime change literature. The research combines historical, archival research with qualitative research methods including interviewing and fieldwork. Fieldwork in the two countries extended over a period of 8 months between December 2015 and December 2016.  Throughout this period of time, I have conducted 43 interviews with activists in the anti-corporatist labor movement, and social movements activists as well as experts who examined similar themes.