The Treaty on the Prohibition of Nuclear Weapons (TPNW), adopted by the United Nations General Assembly in July 2017, has been met with mixed reactions. While supporters have described the Treaty as a watershed in the struggle for disarmament, others have expressed fervent opposition. One of the most serious charges levelled at the TPNW is that it will undermine the long-standing nuclear Non-Proliferation Treaty (NPT), by many regarded as a cornerstone of the international security architecture. Critics have contended that the new agreement risks eroding the system of safeguards designed to prevent the spread of nuclear weapons, derailing disarmament efforts within the NPT framework, and aggravating political division between nuclear and non-nuclear powers. Investigating the legal and political cogency of these arguments, we argue that not only may the TPNW be reconciled with existing legal instruments, the new Treaty supports and reinforces key norms and institutions on which the nuclear non-proliferation and disarmament regime is based. Furthermore, any technical challenges that might arise in the future may be addressed at meetings of states party; the drafters envisioned a dynamic process of institutional adaptations and expansion. The main challenge facing advocates of the Treaty is political: convincing the nuclear-armed states to disarm.