This chapter presents an introduction of the historical regional context in which the Southeast Asia Nuclear Weapons Free Zone (SEANWFZ) was established through the Bangkok Treaty. Later, the four hypotheses outlined are assessed and some conclusions are drawn from this case study. First, the idea of the SEANWFZ was aimed at targeting the superpowers’ presence in Southeast Asia, their military bases and their nuclear weapon arsenals. Second, democracy seems to not have been relevant for the establishment of a NWFZ since democracy rarely existed in Southeast Asia. The exception is the Philippines, where its democratization in the 1980s led to the end of the US military presence and hence the reconsideration of the SEANWFZ. Regional institutions and regional economic cooperation facilitated the establishment of the NWFZ. The SEANWFZ should be seen as an incremental thirty-year process of regionalization while the Bangkok Treaty was negotiated by the Association of Southeast Asian Nations (ASEAN). Third, this case study shows that Indonesia was the leading force behind the NWFZ. Last but not least, normative commitment to non-proliferation was also shared by Southeast Asian countries, and some countries such as Indonesia adopted a high profile in this realm.