This paper focuses on external peacebuilding efforts in areas where the territorial integrity of the state is contested. It conceptualizes external interventions in post-conflict states as interactive processes in which interveners and intervened need to negotiate diverging understandings and interests. With Bosnia and Herzegovina as a case study, the paper inquires into the interaction and negotiation processes between the political leadership of Republika Srpska (RS) and the external interveners around Republika Srpska’s degree of autonomy in a future, post-intervention, Bosnian state. Explanations of the limited success of peacebuilding in Bosnia have often pointed to the dysfunctional institutional structures created as part of the Dayton Agreement. While the ‘blurred’ sovereignty created in Dayton indeed appears to block rather than facilitate the re-integration of the Bosnian state, this paper takes a slightly different approach. It focuses on the means and strategies by which the actors involved use this framework to influence the peacebuilding process to their favor. During the initial years of intervention, international peacebuilding focused on the implementation of the Dayton Agreement. With international oversight in Bosnia drawing to an end, efforts by the interveners to overcome the institutional structure created in Dayton intensified, as did resistance by the RS leadership. Reform proposals by the interveners are adopted selectively, they are blocked, resisted, implemented superficially or circumvented. The ‘real-life’ results of peacebuilding in contested states can be understood as the result of such an interactive process. Based on two field research trips in April/May 2010 and 2011, the paper will draw on the debates around the closure of OHR and around constitutional reform to investigate how and when actors are capable to turn such processes to their favor, what practices are employed in interaction, and how such action is legitimized by those involved.