Few agreements have become the focus of such dramatic domestic and international events as the EU-Ukraine Association Agreement. This article discusses the evolution of the Agreement against the background of Ukraine’s relations with the EU and post-Soviet regional integration projects. We argue that negotiating a binding and comprehensive agreement on deep integration with the EU has been a long-term priority for Ukraine. This is in contrast with its cautious and selective approach to post-Soviet integration initiatives, prizing above all free trade without exemptions. The desire to achieve and maintain this objective has made Ukraine vulnerable to Russia’s regional integration plans which increasingly have entailed a veto on Ukraine’s engagement with the EU through the Association Agreement. The article discusses Russia’s key objections to the Agreement, arguing that they are driven by regional ambition and the need to assert the precedence of its integration regime over the EU. While the overlap of integration regimes is not a unique phenomenon in the modern world, clearly the Association Agreement has shown the limits of EU’s and Russia’s regional economic integration policies with regard to their shared neighborhood. Postponing the implementation of the Agreement as a result of Russia’s objections, however, does not address the core underlying issues behind these limits and creates significant problems of its own. While the crisis over the Agreement has brought up the need for effective inter-regionalism, finding sustainable solutions remains a considerable challenge.