This introductory chapter provides a comprehensive overview of the Biological Weapons Convention (BWC), which entered into force in 1975 as the first multilateral treaty to ban an entire class of weapons. It traces the historical development of biological weapons, early international efforts at regulation, and the negotiation of the BWC during the Cold War. The chapter outlines the Convention’s structure, central prohibitions, and its innovative reliance on the “general purpose criterion” to ensure technological neutrality. Despite its enduring normative strength and near-universal membership, the BWC lacks a binding verification regime, an issue that has persisted across decades of review conferences and negotiation efforts. The chapter reviews past initiatives to strengthen compliance, including the Ad Hoc Group process and the establishment of the Implementation Support Unit. It also considers the future of the BWC in light of accelerating biotechnological advances, renewed verification discussions, and global challenges such as disinformation and dual-use research.