This thesis examines the extent and the nature of city-to-city co-operation (CTCC) for sustainable development among UK local authorities. Policy-makers and analysts believe that various forms of local authority co-operation, here termed CTCC, will enable local authorities to effectively deliver local sustainable development objectives. To date, little attention has been given as to why and how such governing processes take place or to the realities of their outcomes. The thesis informs academic debates on governance. It argues that the 'hollowing out' (Rhodes, 1997, p. 138) and changing role of the state (MacLeod and Goodwin, 1999) have allowed for the emergence and diffusion of self-organizational networks. This shift in the nature of govemance has ted the political opportunity for CTCC. The thesis draws on the policy networks (Marsh and Rhodes, 1992) and govemance networks (Marcussen and Torfmg, 2003) literature to consider how key characteristics in governing through networks - resources, face-to-face interaction, and inter-personal relationships and trust - are relevant to CTCC.