This thesis examines the emergence and evolution of the Afghan Local Police (ALP), a pro-government militia supported by the US military as an entry point for exploring the fluid security and political terrain of post-2001 Afghanistan. The study reveals how the ALP emerged as a compromise between the US ambition to scale up the use of local militias and the Afghan president's attempts to control the local armed groups and the flow of patronage that the US support to these groups represented. The existing literature on the ALP is highly normative and based on limited empirical evidence. Applying the extended case method, this thesis documents the processes through which the ALP was established in three Afghan provinces: Wardak, Baghlan and Kunduz. It demonstrates that the impact of the programme was not unequivocal; the varied outcomes depending on how the programme intersected with local political landscapes. In Wardak, an already fragmented military context was further exacerbated by the injection of US-backed militias, negatively affecting local security. In Baghlan, the ALP emerged as a vehicle for politically marginalised Pashtun groups to re-negotiate Jamiat and Tajik dominance of provincial power structures. In Kunduz, the ALP was appropriated by a Jamiat-led coalition of local commanders and served to preserve the political status quo. This research is the first historically situated, empirically grounded analysis of the role played by militias in local conflicts and processes of state formation in post-2001 Afghanistan. It builds on newer and older debates in historical political economy literature and a range of disciplines in the social sciences about the intertwined relationship between coercion, resources, and patrimonial politics in processes of state formation, and the problems that a historicised political economy approach emphasising the violent foundation of the state raises for liberal understandings of the state. Through a consideration of Afghanistan's modern history and a detailed analysis of the role played by local militias in the political dynamics of three provincial settings, this thesis foregrounds the centrality of violence, transnational resource flows, and elite bargaining to the emergence of state structures in post-2001 Afghanistan. It makes important theoretical and empirical contributions to an expanding body of literature on violence, local militias, policing, and the contentious politics of statebuilding.