The Union of South American Nations (Unasur) presents the most recent vision for trade liberalization and political, economic, and social integration amongst South American countries. Unasur has set 2019 as the year by which it hopes to accomplish many of its goals, such as full regional integration and tariff elimination. But, as 2019 slowly approaches, it remains to be seen whether Unasur will in fact be able to reach these goals. While Unasur’s future is certainly compelling, before heralding Unasur as the long-awaited panacea for pure regional integration, important lessons can be drawn from previous attempts at and iterations of South American regional integration as well as from the model upon which Unasur is structured — the European Union. But what are these lessons, and how do they apply to Unasur? This article will explore the attempts and/or models of Regional Trade Agreements that led up to the creation of Unasur and will then turn to an assessment of Unasur’s successes, failures, the challenges it must face, and an analysis of potential lessons that Unasur may draw from other Regional Trade Agreements.