The role of non-governmental organizations (NGOs) is examined in nuclear weapons related negotiations in the 1990s regarding the Partial Test Ban Treaty (PTBT), the Comprehensive Test Ban Treaty (CTBT), the Nuclear Non-Proliferation Treaty (NPT), and the Statute of the International Criminal Court (ICC). Such negotiations have been an occasion for NGOs to voice public aspirations for an end to the nuclear threat, and in this way to help stimulate some progress, but generally not to influence substantively the terms of the instruments under negotiation. An NGO initiative led to the failed PTBT Amendment Conference which however helped to spur the eventual successful negotiation of the CTBT. At the NPT Extension Conference, one coalition of NGOs assisted in the achievement of US government objectives of obtaining indefinite extension and commitments to negotiation of a CTBT and a fissile materials production cutoff. Other NGOs advocating the abolition of nuclear weapons failed to decisively affect the outcome of the Conference, but the experience served as the catalyst for the development of an ongoing large international network. NGOs seeking the express criminalization of the employment of nuclear weapons in the ICC Statute succeeded only in preserving issues with regard to indiscriminate weapons for future negotiations. NGOs' access to the negotiations regarding the CTBT and NPT was extremely limited. Effectiveness of NGOs in this field could be enhanced by increasing access; by forming closer working relationships with states supporting nuclear disarmament; and by intensifying the interaction between NGO advocacy at the national and international levels.