Abstract:The legitimacy and accountability of polycentric regulatory regimes, particularly at the transnational level, has been severely criticised, and the search is on to find ways in which they can be enhanced. This paper argues that before developing even more proposals, we need to pay far greater attention to the dynamics of accountability and legitimacy relationships, and to how regulators respond to them. The article thus seeks to develop first, a closer analysis of the significance of the institutional environment in the construction of legitimacy, the dialectical nature of accountability relationships, and the communicative structures through which accountability occurs and legitimacy is constructed. Secondly, it explores how regulators respond, or are likely to respond, to multiple legitimacy and accountability claims, and of how they themselves seek to build legitimacy in complex and dynamic situations. This analysis, as well as being of intrinsic interest, could be of use to those trying to design accountability relationships or seeking to build them on the ground. For until we understand the implications of the pressures for accountability and legitimacy, the 'how to' proposals which are proliferating risk being simply pipe dreams: diverting, but in the end making little difference.