Like-minded co-operation has received relatively little attention in the literature of negotiation which traditionally has centered its focus on the study of coalition formation. Nevertheless, this concept of like-minded states is still referred to in various UN settings and often associated with the Nordic countries plus the Netherlands and in some cases Canada. Informal by nature and relatively small in size, this type of group may be defined as a subgroup of actors co-operating to achieve a common goal and influence the outcome of multilateral negotiations. A common trait is that the states forming these groups do not possess power in the traditional sense of the term. In the absence of structural power, these small and medium-sized states seek to gain influence by other means, namely through informal channels that operates within or on the margins of multilateral negotiations. This type of co-operation provides important sources of new ideas, norms and identities in the international system, and when such co-operation succeeds, it often serves to reframe international and domestic debates. The purpose of this thesis has been to draw some general conclusions on why co-operation among like-minded states come into being and what are its prospects for success. Two main research questions have been addressed: First, what may explain the emergence of like-minded co-operation? Second, under what conditions is this type of co-operation likely to be successful? Three independent variables were identified to be of relevance to the first research question; common values and interest, elite networks and triggering events. For the second research question the analysis has focused on the three independent variables relating to the nature of the problem, the nature of the group and exogenous factors. Two empirical cases form the basis of this analysis, illustrating two different situations in which like-minded co-operation has emerged. The first case concerns the like-minded group emerging as part of the negotiations on the New International Economic Order in the mid 1970s. During talks, the negotiating parties were unable to identify a solution and some countries feared a deadlock. With the aim of building a compromise between competing positions, Norway and the Netherlands initiated a like-minded group that was to facilitate the negotiations. The second case concerns a like-mined group known as the Human Security Network that was initiated by Canada as a bilateral partnership with Norway in 1998. Not related to any specific negotiation this value-based co-operation focus on issues that relate to Human Security. The aim of this group has been to act as a promoter on the international arena of ideas and values that relate to a humanitarian agenda. Methodologically this is a process-oriented analysis, taking the nation state as its unit of analysis. Theoretically, this study has tried to make use of the existing contributions in the negotiation literature on coalition theory. This has proved difficult since like-minded co-operation is similar to a coalition, however not identical. The main challenge of this thesis has therefore been to develop a theoretical framework relevant to the study of like-minded co-operation. The study argues that instead of traditional approaches to coalition study, the approaches by Barry Buzan on the formation of informal groups, the contributions by John Kingdon on public policy making as well as the approaches by Kathryn Sikkink and Keck on trans-national advocacy network should be applied.In view of the first research question- why co-operation among like-minded co-operation emerges- the analysis indicates that both common interests and the presence of elite networks seem to have some explanatory value when explaining the emergence of this type of groups. The third variable, that of a triggering event, seem to be of less relevance. As what concerns the second research question- the conditions needed for this type of co-operation to be successful- all three independent variables (the nature of the problem, the nature of the group and exogenous events) seem to hold some relevance. On a more general level this thesis illustrates that like-minded co-operation emerges in different settings, may have different objectives and play different roles inside and outside multilateral negotiations. These initiatives are the results of interest, timing and a common vision by political elites representing small and medium-sized states. The advantage of these networks seems to lie in their informal nature, the non-institutionalization and their flexibility. When this type of co-operation succeeds it represents an important element to be considered when explaining changes on the international arena. As such, they represent an important foreign policy tool that deserves long-term commitment by the states having an interest in this area.