This book critically examines the 25-year journey of the Police Service of Northern Ireland (PSNI) since the radical Patten reforms initiated since the Belfast/Good Friday Agreement of 1998. To what extent did the reforms designed to complement political change succeed in building legitimacy for the police system in Northern Ireland as a shared, impartial institution based on human rights and the rule of law? Drawing on academic research and practitioner experience, including interviews with six former Chief Constables, the authors analyse the challenges of implementation, ongoing struggles with public disorder, legacy issues, and political fragility. Ultimately the book assesses the contribution of policing to Northern Ireland's transition from conflict.