This chapter presents an introduction of the historical regional context in which the South Pacific Nuclear Free Zone (SPNFZ) was established through the Rarotonga Treaty. Later, the four hypotheses outlined are assessed and some conclusions are drawn from this case study. First, the SPNFZ attempted to tackle French nuclear testing and reduce the impact of the superpowers’ arms race on the region. Second, since all South Pacific countries were democracies, the specific role of democracy is not relevant, although domestic factors matter: Labor parties and the antinuclear social movement pushed forward the idea of a SPNFZ in many countries. The South Pacific Forum, the main regional institution, established the SPNFZ, and economic institutions aimed at promoting regional cooperation had a spillover effect on security regionalism. Third, Australia, the main regional power, was the most salient actor in the negotiation process of the SPNFZ, along with New Zealand. In this regard, individual norms entrepreneurs such as prime ministers Robert Hawke (Australia) and David Lange (New Zealand) are highlighted as they pushed for the SPNFZ. Normative commitment was shared across the region, and against the backdrop of the SPNFZ, Australia became a promoter of non-proliferation initiatives.