The Nigerian power sector reform is necessitated by the chronically poor performance of the sector and has as its compass the 2005 Electric Power Sector Reform Act and the Road Map for Power Sector Reform 2010. Implementing the reform has resulted in significant progress that includes unbundling and privatization of the long-standing government-owned monopoly in the power sector and a move towards achieving a cost-reflective electricity tariff. This chapter provides a comprehensive assessment of the reform, isolating the major challenges facing it, and focusing on political economy developments surrounding regulatory, institutional, legislative, and fiscal issues, with achieving energy security and mainstreaming clean renewable energy being the main theme running through the analysis.