Telecommunications has gained in importance in the world economy. Regulation of this industry therefore has become a crucial policy issue of the governments around the world. In the thesis, I examine regulation of telecommunications services in OECD countries. Special attention is given to the New Zealand regulatory regimes before and after the second regulatory reform. As the first regulatory reform in telecommunications in New Zealand occurred over a decade ago, regulatory measures had to be adjusted to suit the current environment. This was the main reason for the establishment of a government-mandated inquiry. Measures were sought and evaluated to reduce or eliminate problems that were associated with the old regime, especially the not-very productive commercial negotiations and the not-very-efficient process and the institution that operators relied on for solving their disputes. I use Coase Theorem to examine why commercial negotiations did not work as effectively as the government envisaged. With the adjustments of regulatory institutions and their functions, the government wishes to counter the time-consuming dispute resolution process that works against new entrants, and to increase the incentive to negotiate. The second regulatory reform shifted the regulatory burden from the courts to the industry and the Commerce Commission. Comparisons of the two regimes are made to analyse the differences of the two regimes to achieve better understanding of the social and economic goals of the New Zealand government. The two regimes are evaluated to provide information on the potential problems that might emerge in the future. Topics such as the difficulties a regulator faces in imposing appropriate regulatory measures, the direct relationships of regulation and competition and the indirect relationships of regulation and telecommunications performance are analysed in depth.