Where do the opportunities for gendered institutional change lay in post conflict transitional states? In particular, what processes explain the transformation of gender roles within traditionally male-dominated sectors such as security? The post-conflict South African State provides the institutional backdrop against which the gender equality gains of women in the security sector are explored. The rare opportunities presented in the transitional context are a key factor in understanding the promises and limits of gendered change within the institutional arena, both in terms of the descriptive and substantive representation of women. This thesis explores the processes of gendered institutional change from a feminist institutional perspective, incorporating a range of normatively nuanced variables that examine the mechanisms by which socially-constructed gender norms are altered within the security sector, situating power at the heart of the contextually driven analysis. The thesis argues that the paths which emerged over the course of the liberation struggle as a result of three key historical legacies enabled a transformation of gender roles and institutional norms with respect to security. Specifically, the intertwined legacies of an equality-based liberation movement, the continuous increase in women’s autonomy, and the legacy of militarisation all contributed to the opening of spaces for women’s strategic action. Through process tracing methodology, the thesis reveals how South African women strategically wielded their power to consolidate gender gains embedded within the foundational documents of the new democratic regime. In so doing, women capitalised on a range of timeous exogenous influences within the broader feminist movement, particularly the global shift towards institutionally-focused gender mainstreaming strategies. The focus on the security sector is viewed as a litmus test for the advancement of gender equality within the institutional structures of South Africa, given the rigidly patriarchal and masculine norms permeating the security arena. Among the contextual considerations which produced openings for the gendering of State security structures was the adoption of the human security paradigm, which called for a holistic, people centred vision of security centred around development and stability. The resulting overhaul of the security sector, and the repositioning of the South African military on the national and regional stage, presented further opportunities for strategic interventions by women to transform the institutional culture of the State security structures. Bolstered by exogenous influences such as innovative regional and international instruments and organisations, a new military culture began emerging in South Africa, with women positioned to play a central role in its development. The manner in which women engaged with this process is a demonstration of the extent to which gendered norms have become entrenched in the institutional structures of the post-conflict South African State, revealing the constraints of inherited structures, and the power of institutional layering in restructuring women’s security roles within the State. The successes and failures of the gendering of the security sector are embodied within the complex case of the arms acquisition. This example is analysed as a “case study within a case study”, and clearly highlights the intersection of the multiple variables discussed in the thesis, revealing the manner in which evolving institutional norms promote and foreclose gendered change, and the implications of the struggle between old and new gendered legacies. The infusion of gendered norms into the security sector is also considered through the perceptions of government and civil society respondents, as an indicator of the “stickiness” of the gender equality rhetoric, and of the progress made towards transforming the masculine domain of the security arena. The unique attributes of the South African case yields insights into the opportunities and constraints of post-conflict institutional change, contributing to the broader feminist institutional literature through the focus on the complex processes of gendered institutional change and continuity within the overlooked security structures of the State.