The first South Sudanese elections in 2010 returned high proportions of women parliamentarians (32 per cent), largely as a result of gender quota provisions. In the case of post-conflict countries such as South Sudan, processes of political restructuring and constitutional ‘engineering’ can present opportunities for issues of women’s political representation to be institutionalised through gender quota laws. However, the gap between formal laws and their implementation in practice can result in uneven outcomes, particularly in the context of deeply entrenched patriarchal attitudes and customs. Furthermore, whilst the comparative literature underscores the importance of factors such as institutional environment, ‘goodness of fit’, and sanctions for non-compliance in explaining successful outcomes, such elements are routinely absent in sub-Saharan Africa. It is important, therefore, to explain the apparent success story of gender quotas in South Sudan. There are few in-depth stories of the implementation of gender quotas. As such, the mix of formal rules and informal norms that plays out in a particular context – i.e. the rules-in-use – has been asserted rather than captured in practice. The thesis argues that tracing these micro processes is particularly important in post-conflict cases where formal political institutions are fragile and embryonic. The thesis aims to: a) tell the story of the adoption and implementation of gender quotas in South Sudan; b) identify key actors (including political parties), institutional processes, practices, and exogenous and endogenous factors contributing to success; c) explore the role of rules-in-use in implementation; and d) problematise the ‘success’ of quotas and future prospects for women by examining formal and informal institutions and their design. The study employs documentary analysis, interviews and observation methods, using a broadly institutionalist approach. Intensive fieldwork in South Sudan was conducted for one year from July 2010 to 2011, including informal discussions and briefings with political, religious and local government elites, female parliamentarians, and experts in the media, international development and academia. The thesis argues that political institutions are gendered, and therefore the understanding of adoption and implementation processes and norms is crucial to understanding both the success and shortfalls of gender quotas. It argues that political elites matter because they frame popular mandates, strategic discourses and the authoritative drive for quotas. Analysing the interaction between old and new institutions, the thesis shows the impact of legacies on outcomes. It argues that institutional design matters because the use of reserved-seat quotas had unintended consequences which diluted the impact of gender quota on the wider system by concentrating women. Although women are not formally confined to quota seats, in practice female aspirants seeking mainstream candidacies encountered considerable resistance, demonstrating the existence of informal norms which constrained their access to political power. The success of gender quotas is fragile and future prospects for women’s representation are uncertain. Gender quotas are constitutionally enshrined and there is continued evidence of rhetorical support. However, the new political institutions are deeply permeated with traditional norms and power dynamics that blunt the reformist potential of quotas and reinforce the gender status quo. The thesis provides a benchmark study of women and political recruitment in South Sudan and contributes a new empirical case to the comparative gender quotas literature, as well as to the regional literature on gender in post-conflict contexts.