This case deals with the efforts carried out by third parties in the resolution of separatist armed conflicts. The basic premises are that multilateral mediation success is the result of the combination of multiple conditions (complex causality) and that more than one path can lead to conflict resolution (equifinality). During the early stages of the research, I recognized that both qualitative and classic quantitative analyses could not effectively account for complex causality and equifinality. As a consequence, I opted for using fuzzy-set qualitative comparative analysis, a relatively new method in the field of international relations and probably the best-suited technique to identify the combinations of factors that affect a certain outcome and the different paths that can lead to a common end state. Moreover, qualitative comparative analysis allows comparison between cases and at the same time offers detailed account of the complexity of each case. Thus, on one hand, qualitative comparative analysis provides the researcher with the tools to gather in-depth knowledge of the cases, and, on the other hand, it also allows to make some generalizations. Using this method, I identified different conditions that contribute to mediation success and analyzed the causal role they played—alone and/or in conjunction with other factors—in solving 20 separatist armed conflicts that occurred in Europe, Asia, and Africa after the end of the Cold war. The case takes the reader through the practicalities of the process of formulating hypotheses, selecting the cases, calibrating the conditions, and interpreting the findings.