This thesis asks the question: How can social movement alliances manage to acknowledge and work across difference in conflict situations? It seeks to add to deeper understandings of movements by examining a complex multi-­‐group movement context in which complicated and very layered tensions were at issue. It seeks to investigate these issues through a case study of tensions between movement actors within the campaign against Shell in North West Mayo, Ireland, between English ecological activists, Dublin and Cork Shell to Sea groups, and Irish members of the Rossport Solidarity Camp. The issue of how to acknowledge and work with difference is a hugely important one for the building and maintenance of contemporary movement alliances for practitioners, and is also an area of interest for social movement scholars. Connected with this, alliance is largely accepted as increasing a movement’s chance of success, and is usually something which is also seen as desirable by movement actors. I undertook my research within a Participatory Action Research (PAR) frame. As such, my research was a highly involved process, within the frames of looking at dynamics of alliance formation, and saw its main themes emerge from the research participants. The tensions that emerged in the campaign were organised around a discourse of colonialism put forward by members of Dublin and Cork Shell to Sea, but the issues also encompassed differences between ecological and class-­‐based ideologies, as well as significant differences between political cultures of direct action, and ones based around political organising. This work is done with the aim of making movement participants intelligible to each other, to widen movement perspectives, and it attempts to begin a process of dialogue and discussion between actors in the campaign against Shell, who have struggled with these issues.