This chapter details how, for several decades, the normative framework for European security has been based on the principles and commitments of the Helsinki Final Act. The Helsinki principles and commitments, the result of more than two years of almost unbroken diplomatic negotiations, became the basis for guiding mutual relations amongst the participating States during the Cold War and helped to smooth the process of post-Communist transition. They remain relevant today as the fifty-seven participating States of the Organization for Security and Co-operation in Europe (OSCE) look to return to a rules-based system in order to enhance predictability, trust, and stability. The chapter looks at how OSCE principles and commitments have contributed to promoting security and cooperation in Europe. It explores how a political body, and the norms articulated by its participating States, fit into the framework of international law, and influence or are driven by it. Moreover, the chapter considers the impact that the unclear legal status of the OSCE has, particularly on operational activities. It analyses the OSCE as a political arrangement, its legal context, its structures, the status of its international legal personality and its impact, the OSCE as a regional arrangement under the United Nations Charter, and the various dimensions of the OSCE’s work.