We survey the theoretical literature on privatization and efficiency by tracing its evolution from the applications of agency theory to recent contributions in the field of political economy. The former extend the theory of regulation with incomplete information to address privatization issues, comparing state-owned enterprises with private regulated firms. The benefits of privatization may derive either from the constraints it places on malevolent agents or from the impossibility of commitment by a benevolent government because of incomplete contracts. Contributions dealing with political economy issues separate privatization from restructuring decisions. They either explore bargaining between managers and politicians or analyse the impact...