The Comprehensive Test Ban Treaty (CTBT) and the Treaty on the Prohibition of Nuclear-Weapons (TPNW) are two decades apart but both were spurred on by heightened expectations of nuclear disarmament. This chapter revisits the multilateral negotiations that led to these agreements and conducted research about them. The aims are to (1) generate insights of relevance for the current situation of nuclear diplomacy stalemate, (2) extract lessons of utility for future negotiations, and (3) identify knowledge gaps to encourage further research. The research overview has a comparative feature, which helps to identify recurrent obstacles in both negotiations, and main shifts that has taken place between them. Both negotiations are associated with ‘emotionalized polarization’ between the nuclear weapons states and groups of non-nuclear states, concerns with treaty design, and security-justified dropouts. Between these negotiations there has been an institutionalization of coordination among the nuclear weapons states, and an amplification of the ethical dimension in the critique against nuclear weapons. From the study of negotiations, the chapter utilizes the analytical framework of formula and detail to address the current nuclear diplomacy stalemate. Parties have drifted from the original formula that paved the way for the Nuclear Non-proliferation Treaty (NPT), wich affects the chances to reach further agreements. As an implication for policy, diplomacy needs to establish opportunities for parties to formula re-commitmen to facilitate progress on detail. As for future research, it is relevant to consider expanding the study of formula influence from single negotiations to the post-negotiations within the international regime that an original agreement has established.