In contrast to the once prevailing norm of secrecy and opaqueness, transparency has now become one of the main features characterising the conduct of monetary policy. Detailed analysis of eleven OECD central banks shows that communication practices have converged markedly in the direction of ever greater transparency. Empirical evidence is consistent with the hypothesis that transparency contributes to the successful conduct of monetary policy: higher transparency is a typical element of monetary frameworks that are associated with better anchored inflation expectations and more stable inflation outcomes. Despite this general trend toward increased transparency, however, central banks differ in actual communication practices. There is a particular divergence with respect to transparency in the decision-making process and communication regarding future policy inclination. Although the appropriate degree of transparency in these areas is an unsettled issue, the fact that financial dislocation is impairing conventional monetary transmission makes these two areas critical for policy implementation.