The North American Free Trade Agreement (NAFTA) and the Energy Charter Treaty (ECT) are the first major multilateral treaties to impose obligations on governments concerning the protection and treatment of foreign investments. These obligations are enforceable by private companies. NAFTA and the ECT examines the effectiveness of the investment rules of these treaties and analyzes the mechanisms adopted to enhance compliance, and to facilitate the implementation and enforcement of the relevant rules and regulations. Coverage of this work includes: a conceptual analysis of the precise meaning and theoretical foundation of compliance, implementation, and effectiveness; an examination of issues of direct effect and direct international responsibility in terms of the practical question of the treaties' impact on the domestic regimes of states; an exploration of the issues of transparency and monitoring to achieve enhanced compliance; and a close look at a number of key links in the field - between the investment rules and the workings of national legal and governmental systems, between national and international law, between different disciplines involved (international law, international relations, international politics, and economics), and between transparency and compliance monitoring. NAFTA and the ECT also offers several helpful features, including results from a questionnaire-based survey circulated to the main players in the realm of foreign investment which offer insights on the prevalent perception of the industry towards NAFTA and the ECT; and suggested provisions and frameworks which would enhance the effectiveness of the investment rules. The issues probed and conclusions reached and the interdisciplinary and comparative approach taken should make NAFTA and the ECT a a useful resource for academics, policymakers, and others interested in the effectiveness of international investment agreements and the tools employed in their implementation and enforcement.