Why did the Dutch hold on to Western New Guinea, one of the many territories that constituted the Dutch East Indies (modern-day Indonesia), when the colony became independent in 1949? This thesis argues against the traditional explanation that it was due to a singular Dutch ‘decolonization trauma’: an inability to let go of the glorious colonial past, combined with resentment against Indonesian nationalist leaders such as Sukarno. It shows that historians have overstated the importance of emotions in Dutch colonial policy-making and diplomacy after 1949, mainly because of their narrow scope of analysis, which has traditionally been restricted to trilateral relations between the Netherlands, independent Indonesia (which wanted to incorporate Western New Guinea, if need be with military means) and the allegedly ‘anti-colonial’ United States. This thesis situates Dutch decision-making in the Western New Guinea Crisis in a much wider network, incorporating the colonial policy, diplomacy and perception of other Western powers such as Britain, France, Australia, Belgium and Portugal between 1930 and 1962. It is argued that, when viewed within this network and its discourse, the Dutch decision to retain Western New Guinea is best explained with rational actor theory. The decision was inspired not so much by emotions as by cost-benefit analyses, which included the possibility of transferring the territory to a new Indonesian regime—which the Dutch expected to be more forthcoming to the interests of the Papuans, the native inhabitants of Western New Guinea, and the Dutch (economic) interests in Indonesia than the regime headed by Sukarno. Research into hitherto neglected French, Belgian, British and Dutch archives also shows that the Netherlands could count on much more support for its New Guinea policy from its Western allies—including the US—than traditional historiography suggests. It remains true that the United States forced the Netherlands to hand over Western New Guinea to Indonesia in 1962, but the Kennedy ...