To what extent should public utilities regulation be expected to converge across countries? When it occurs, will regulatory convergence lead to positive outcomes for utility sectors? This paper attempts to provide new answers to these questions. Building on the core proposition of the New Institutional Economics (NIE) that similar regulations generate different outcomes depending on their fit with the underlying domestic institutions, we develop a simple theoretical model and explore its implications by examining the diffusion of local loop unbundling (LLU) regulations in the telecommunications sector. We find support for the ideas (1) that once institutional factors are taken into account, one should expect some convergence in public utility regulation but with still a significant degree of local experimentation, and (2) this process will lead to very different results regarding the impact of regulation.