This article investigates whether the overlapping of intergovernmental regional organizations in Latin America with regard to membership and mandate is harmful or beneficial to regional cooperation (with a special focus on mediation in domestic and international conflicts). The article begins by systematizing the discussion about the possible risks and potential benefits of overlapping regional organizations, and then outlines hypotheses that can be tested in concrete episodes of overlap of action. The article then analyzes nine episodes in which an overlap of action has occurred between two Latin American organizations, the Organization of American States (OAS) and the Union of South American Nations (UNASUR). The results of the study are mixed. However, the effects of overlapping seem to be much less problematic than a large body of literature generally assumes.