AbstractAmong the 104 churches signatory to the Leuenberg Agreement of 1973, which created ecclesial communion between Lutheran, Reformed, and United churches in Europe, are six churches from Latin America, five of them from the Southern Cone. This article reviews how the Protestant churches in the Southern Cone came to be signatories of the Leuenberg Agreement and its significance for their life and witness. Two elements in particular have proven significant over the years. The first is the theological and ecumenical platform the Leuenberg Agreement provided, which gave visibility to a phenomenon already taking place. The second is the fact that the Communion of Protestant Churches in Europe has a regional group in South America: this was the case almost from the beginning, which also poses an interesting theological and contextual challenge.